I was supposed to be preparing for last week’s AMSA RMC Exchange Live webinar. Instead, I distracted myself by rereading something Gary Taubes published almost exactly a year ago1 that got me thinking again about calories. Or, more precisely, about counting them. I tried to raise some of these questions during a Q&A at the recent metabolic health conference in San Diego. I don’t think I succeeded in making the point clearly. Apparently procrastination sometimes produces Substack posts.

This isn’t the first time I’ve ruminated here about the difference between what we think was eaten and what was actually consumed. A few weeks ago, the Ruminati Word of the Week was “orts”—the feed left behind by an animal.2 Animal nutritionists account for orts because what we offer an animal isn’t necessarily what the animal eats. That distinction is so elementary that we have a word for what’s left over.

That earlier rumination was mostly about protein. This one is about calories.

Because once I started thinking again about the extraordinary precision supposedly required to maintain energy balance, another question occurred to me:

How precisely could we possibly know how many calories—or grams of protein, fat, and carbohydrate—a free-living human actually consumed in the first place?

Of Course Energy Is Conserved

Let’s get something out of the way immediately. The First Law of Thermodynamics applies to human beings. Of course it does. If the amount of energy stored in a body increases (the body gets bigger for any reason), more energy must have entered that body than left. If stored energy decreases, the reverse must have occurred. But as Gary has emphasized for years, there is no arrow of causality in the energy-balance equation.

If someone accumulates body fat, energy balance tells us what happened. It doesn’t tell us why it happened. Did the person store fat because they ate more? Or did physiological changes favor energy storage, alter access to stored fuels, affect hunger and satiety, and therefore cause them to eat more?

Did energy expenditure decline? If so, why? Did someone become less active and therefore gain weight, or did changes in metabolism and available energy make them less inclined to be active?

Did thermogenesis change? Fuel partitioning? Hormonal signaling? Hunger? Satiety?

The energy-balance equation cannot answer those questions.

Saying that someone became obese because they consumed more calories than they expended is rather like explaining why a reservoir rose by saying that more water entered than left. Correct. Necessarily correct. But it doesn’t tell us why the reservoir rose.

Energy balance is an accounting identity. It is not, by itself, a causal explanation.

Then There’s the Precision Problem

Gary has made another point that has fascinated me for years.

Consider someone consuming about 2,700 calories per day. That’s roughly one million calories per year, or ten million calories over a decade. How closely would intake and expenditure have to match to limit weight gain to, say, 20 pounds over that decade? Using the conventional arithmetic, Gary calculates the discrepancy at roughly twenty calories per day3—less than 1% of daily energy intake. In fact, Taubes reports Eugene F. Du Bois (1882–1959) calculating that long-term energy intake and expenditure would have to balance to approximately 0.05%, which Du Bois described as:

“an exactness … which is equaled by few mechanical devices.”4

Yet many people maintain remarkably stable body weights for years or even decades. Think about what that means.

If conscious matching of “calories in” and “calories out” is what maintains body weight, then somehow we’re expected to match two enormous and continuously varying energy flows with extraordinary precision—day after day, year after year. Without actually knowing either number. That alone ought to make us curious about what is really regulating body weight. But I want to add another problem.

What if we tried to count those calories? Could we do it accurately enough?

How Many Calories Were in That Steak?

This was part of what I tried, unsuccessfully, to get at in San Diego. Dave Feldman famously photographs everything he eats, maintaining an extraordinary record of his food intake for years. In his experiments, he can be considerably more rigorous still.

I want to emphasize this because I don’t want the following point misunderstood: I’m not criticizing Dave. Quite the opposite. Dave provides a remarkably good example because his food intake recording is probably far better than that of virtually any other free-living person.

Suppose Dave photographs a steak before eating it. Better yet, suppose he weighs it. Now we have very good evidence of what Dave ate and how much it weighed. So how many calories did Dave consume? We could enter the weight into a tracking app. The app could consult a food-composition database and tell us it was 743 calories. But did that steak contain 743 calories? We don’t know. Unless somebody chemically analyzed that particular steak, the number comes from a database representing some other sample or, more likely, an average of samples.

How much separable fat did Dave’s steak contain? How much intramuscular fat? How much water? Was the database entry for raw or cooked beef? How much water was lost during cooking? How much fat rendered out? How much remained in the pan or on the plate? (To be fair, Dave also photographs what’s left on his plate at the end of the meal)

The same problem exists with virtually every food, and it becomes progressively more complicated with mixed dishes. The computer may display 743 kcal, but those three digits don’t mean that we measured Dave’s energy intake to three-digit accuracy.

743 is the precision of the calculation, not the precision of the measurement.

Now Read the Label

Packaged food doesn’t solve the problem, either. The numbers printed on a Nutrition Facts panel aren’t assays of the exact food you’re holding in your hand.

Food and Drug Administration (FDA) nutrition-label compliance procedures themselves recognize substantial analytical and product variability. For calories, total sugars, added sugars, total fat, saturated fat, trans fat, cholesterol, and sodium, FDA evaluates laboratory analysis of a composite sample against the declared label value; the analyzed amount may be as high as 120% of the declared value before exceeding the agency’s compliance criterion.5 In other words, even the regulatory system isn’t pretending that the number printed on the package is an exact measurement of the particular serving you’re about to eat. That's not a criticism of FDA. It's an acknowledgment of the biological and analytical reality: food composition isn't exact.

Then consider the other variables: Did you eat exactly one serving? Did you weigh it, and if so, how accurate is your scale? Did you finish everything, or was there butter left in the pan, dressing left in the bowl, meat juices on the plate, etc?

Now try doing this with a casserole. Or chili. Or a restaurant meal. Or Thanksgiving dinner.

Orts, anyone?

And remember what we’re supposedly trying to detect: perhaps tens of calories per day against a background of thousands.

The Arithmetic Is Precise. The Inputs Aren’t.

This is what bothers me about the apparent precision of calorie and macro tracking. A tracking app might tell me that yesterday I consumed:

2,137 kcal
127 g protein
83 g fat
191 g carbohydrate

Those numbers certainly look like measurements, but they aren't. They're calculations performed on estimates. And additional decimal places don't make an estimate more accurate. The food-composition values are estimates. Portion sizes may be estimates. Mixed-meal composition may be estimated. Food preparation introduces additional variation. What was actually swallowed differs from what was served. And that’s before we get to perhaps the largest problem of all: free-living human beings are notoriously imperfect reporters of what they eat.

Yet after combining all those uncertainties, software can return a number to the nearest calorie and gram.

The arithmetic is precise. The inputs aren’t.

That doesn’t make tracking necessarily useless.

Someone who records food intake may become much more aware of what they’re eating. Tracking may reveal patterns. It may help someone change behavior. Tracking carbohydrate or protein may be particularly useful when the objective doesn’t require knowing intake to the nearest gram.

Approximation can be useful, but useful approximation should not be confused with precise measurement.

And that distinction becomes rather important if we’re told that maintaining body weight depends upon consciously balancing energy intake against expenditure with a precision of considerably less than 1%.

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Ask an Animal Scientist

Here’s where my agricultural background makes this especially interesting to me.

When animal scientists actually need to know how much an individual beef or dairy animal eats, what do we do? We don’t give them an app and we certainly don’t ask them what they remember eating. Modern individual-feed-intake systems can electronically identify each animal. Automated equipment can measure feed disappearance. The feed itself is characterized. Dry-matter content matters. Animals are weighed. Measurements are collected repeatedly.

And we don’t do this for a work week (you know how tricky weekends can be!).

Beef Improvement Federation guidelines6 recommend at least a 21-day acclimation period and a 42-day intake test, typically providing at least 35 days of reliable intake measurements. BIF explicitly recognizes that both intake and gain measurements contain error and that testing procedures and instrumentation must be designed to minimize it.

Think about that.

Electronic identification.
Instrumented feeders.
Characterized diets.
Repeated measurements.
Weeks of data collection.

And after all of that, animal scientists still talk about measurement error.

At Hickory Nut Gap Farm earlier this month, my friend and colleague Dr. Matthew Calkins made a related observation while contrasting the quality of Beef Improvement Federation data collected from bulls on feed with the Food Frequency Questionnaires commonly used in human nutritional epidemiology.

Imagine applying an FFQ to cattle:

Over the past six months, how frequently did you consume grass hay? Never? Once per month? Two to four times per week? Daily?

When you ate corn silage, would you characterize your usual serving as small, medium, or large?

It’s clearly absurd, but the absurdity helps make the point. When we really want to know how much a bull ate, we don’t ask it what he remembers eating. We instrument the animal and its feeding environment because measurement quality determines the quality of the inference.

And Dave Is Better Than a FFQ

Which brings me back to Dave and his food photographs. They are vastly better evidence of what Dave ate than asking him six months later to reconstruct his “usual” dietary intake.

That’s precisely why I find his example useful.

He can photograph everything.
He could weigh almost everything.
He can record everything.
He can be more meticulous about documenting his diet than almost anyone I know.

And we still cannot know his caloric intake to anything approaching the precision supposedly required for conscious long-term energy balancing. The limiting uncertainty isn’t Dave. It’s the food itself, the database, the preparation, and the measurement.

And we've only been talking about “calories in.” To consciously balance the equation, we'd also have to know “calories out” with comparable precision.

So What Are We Actually Regulating?

This brings us back to Gary’s original point.

An average adult may consume and expend something approaching a million calories each year. Yet body weight can remain remarkably stable. The organism accomplishes this without consulting Nutrition Facts panels, opening a tracking app, or knowing its energy expenditure. That ought to tell us something. The relative stability of adult body weight over long periods is itself evidence of biological regulation.

“There is no stranger phenomenon than the maintenance of a constant body weight under marked variation in bodily activity and food consumption.” Eugene F. Du Bois7

The scientific question isn’t whether energy is conserved. Of course it is.

Nor is the interesting question whether calories “count.” Of course energy counts.

The interesting questions are:

What regulates the flows?
What regulates hunger and satiety?
What determines whether incoming energy is oxidized, dissipated, incorporated into lean tissue, or stored as fat?
What regulates access to energy already stored in adipose tissue?
What determines spontaneous activity and thermogenesis?
How do food composition, hormonal signaling, metabolic state, and fuel partitioning affect all of these?

Those are questions about physiology and causality. “Calories in, calories out” cannot answer them because there is no arrow of causality in the equation.

And “just count your calories” introduces another problem altogether.

“Just count your calories” asks a free-living human being to consciously regulate a biological system to a degree of precision that would be extraordinary even if we could accurately measure the variables.

We can’t.

Which strongly suggests that we should redirect our attention from trying to count the flows to understanding what regulates them.

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1

This train of thought was prompted by rereading Gary Taubes’s August 2025 essay,

Uncertainty Principles

Fighting Obesity? The New England Journal of Medicine Has a Calorie Fixation

Quiz of the week…

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a year ago · 145 likes · 13 comments · Gary Taubes

“Fighting Obesity? The New England Journal of Medicine Has a Calorie Fixation.” His argument is worth reading in full.

We talk a lot about food. Food production. Food security. Food prices. Food waste. Food policy. Sustainable food. Food systems. But what is food?

That may sound like a silly question. Surely we all know food when we see it. Or do we?

Before asking what kind of food system is sustainable, perhaps we should first ask a more fundamental question: What must that system accomplish?

Surely a food system must first nourish human beings. Which leads to another deceptively simple question: What does “nourish” mean?

What do you mean by “meat”?

Even the names we give foods aren’t as straightforward as we might think. Ask people from different cultures how often they eat “meat” and you may get very different answers—not simply because their diets differ, but because meat may mean different things to them. Someone might tell you that meat is eaten only occasionally: on Sunday, at a celebration, when guests visit, or on some other special occasion. Yet that same person may consume some form of muscle or variety meat every day. Small amounts of meat, fresh or processed, may be incorporated into soups, stews, sauces, or mixed dishes. But that isn’t necessarily what the person means by “meat.” Eggs, milk, cheese, fish, or other animal-source foods may be seen more as ingredients, too.

The special piece of meat at the center of a celebratory meal is meat. The animal-source foods incorporated into everyday meals may simply be food. Language matters. Culture matters. And food is deeply cultural.

Think about the foods associated with your own childhood. What did your family eat at holidays? What was served when relatives came to visit? What dishes did your parents or grandparents prepare? Which foods immediately remind you of particular people, places, or events? Recipes pass between generations. So do techniques for growing, harvesting, preserving, fermenting, curing, cooking, and serving foods.

Food carries history. Food expresses hospitality. Food accompanies celebration and mourning. Food is associated with religious observance, geography, seasons, livelihoods, and community.

So already our definition is becoming more complicated. Food is something humans eat. But food is also something humans do.

Take a walk through the supermarket

Now consider a typical American supermarket. Walk around the outside. Produce, meat, eggs, dairy, seafood. The perimeter isn’t a perfect dividing line. The bakery and deli may be there as well. Meanwhile, frozen vegetables, canned fish, coffee, and many other recognizable foods are found in the interior aisles. But walk those center aisles and something changes. Boxes, bags, bottles, cans, and jars. Some contain foods that have simply been preserved or packaged. Others contain products assembled from ingredients that have been extracted, refined, fractionated, concentrated, recombined, flavored, colored, stabilized, emulsified, and packaged. And we call all of it “food.”

Estimates suggest that roughly 70 percent of the U.S. food supply consists of products commonly classified as ultra-processed (a category that may be a topic for another time). More than half of the calories consumed by American adults—and an even greater proportion of those consumed by children and adolescents—now come from ultra-processed foods.

I’m not suggesting that processing is the problem. Humans have processed food for a very long time. We cook, grind, dry, smoke, ferment, and cure. We transform milk into cheese or we separate the cream and churn it into butter. Traditional food cultures are, in part, collections of technologies for transforming biological materials into foods that are safer, more digestible, more storable, more nutritious—or simply more delicious.

But there seems to me to be a meaningful distinction between processing food and manufacturing an edible product.

Which raises our question again: What is “food”?

Edible biomass

I’m an agronomist, so perhaps I approach this question differently. Agriculture produces biomass. In fact, I’ve come to describe agriculture this way:

The history of agriculture is the story of humanity modifying its environments to produce more edible biomass.

Takes some of the romance out of it, doesn’t it? Perhaps “edible” is where some of the confusion begins, since edible biomass and food aren’t necessarily synonymous. A substance can be edible and provide calories while failing to provide adequate essential nutrition. Likewise, two foods providing the same number of calories may not be nutritionally equivalent. Nor are two foods containing the same number of grams of “protein.” Protein isn’t just protein.

Human beings require particular amino acids. Their amounts matter. Their proportions matter. Digestibility matters. Bioavailability matters. The same is true of minerals, vitamins, essential fatty acids, and other nutrients. Animal-source foods aren’t simply sources of protein. They provide a veritable basket of highly bioavailable essential nutrients.

And even that description may be incomplete. There is evidence for a “meat factor,” for example: eating animal-source foods can improve the utilization of nutrients such as iron and zinc from other foods in the same meal. Foods interact. Meals matter. Reducing foods to their individual nutrients can obscure something important about food itself.

From adequacy to “negative nutrition”

During my presentation at the Symposium for Metabolic Health, I showed this American nutrition poster from 1943.

Its message seems almost quaint today: “For health, eat some food from each group every day.”

The question underlying that advice was essentially: “What must people eat to be adequately nourished?” Nutrition was concerned with adequacy. Later, the emphasis changed. Adele Hite called what followed “negative nutrition.”

Instead of asking primarily what people needed to eat, nutrition increasingly told us what to eat less of.

• Fat. Then saturated fat.

• Cholesterol.

• Meat and other animal-source foods.

• Salt.

• Sugar.

The dominant question had changed from “What do we need?” to “What should we avoid?” At the same time, the scale and nature of our malnutrition problem were changing. Classical nutrient deficiencies certainly haven’t disappeared. They remain an enormous burden in many parts of the world—and within populations in affluent nations. But we now coexist with another enormous problem: chronic metabolic dysfunction, manifesting as obesity, type 2 diabetes, cardiovascular disease, fatty liver disease, and a growing collection of other disorders associated with impaired metabolic health.

People can consume an abundance of edible material—an abundance of calories—and still be poorly nourished. Overfed but undernourished. Even malnourished. That possibility should fundamentally change the way we think about food systems.

Nutrients aren’t nourishment

I don’t want to make the opposite mistake. If food isn’t merely calories, neither is it merely a more sophisticated list of nutrients. Nutrition science has taught us a great deal by taking foods apart—identifying and understanding their proteins, fats, carbohydrates, amino acids, fatty acids, vitamins, minerals, and other components. That knowledge matters. But people don’t eat nutrient tables. We eat foods. We eat meals. And hopefully, we share many of those meals with other people.

A shared meal can nourish something that isn’t measured in grams or milligrams. Food connects generations. It reinforces families and communities. It gives us occasions to gather. It preserves knowledge and carries traditions forward. It connects people with particular plants, animals, landscapes, and seasons. It provides livelihoods.

There is more to nourishment than nutrients.

A nutritionally complete formulation consumed alone might satisfy every biochemical requirement we can currently measure. Would we really consider that the full meaning of being nourished? I wouldn’t.

We need nutrients. But we are nourished by food.

What is the purpose of a food system?

This matters because the answer determines what we mean by a “sustainable food system.”

We measure agricultural systems in all sorts of ways.

• Yield per hectare.

• Kilograms of food.

• Calories.

• Grams of protein.

• Water use.

• Land use.

• Greenhouse-gas emissions.

Those measurements can be useful, but for what? Every measure contains, explicitly or implicitly, an assumption about what the system is supposed to accomplish. If the objective is producing the greatest quantity of edible biomass, one agricultural system may appear optimal. If the objective is calories, another may. If we measure crude protein, we may get another answer. If we ask about digestible indispensable amino acids, the ranking may change. If we ask about providing the complete basket of essential nutrients humans need in bioavailable forms, it may change yet again. And if the objective is human nourishment and flourishing, the accounting becomes more complicated still.

Now we must ask what happens after something leaves the farm. Production isn’t provision. Agriculture produces commodities. Those commodities enter systems of processing, distribution, marketing, retail, food service, cooking, and consumption.

What does the agricultural commodity eventually become? Who can afford it? Who has access to it? What does it replace in the diet? What happens metabolically when people consume it? Does the resulting diet improve health—or contribute to disease? And what happens to the families, communities, livelihoods, traditions, and landscapes associated with producing and eating it?

If the purpose of a food system is to nourish people, why should our assessment of that system stop at the farm gate, processing plant, supermarket checkout—or dinner plate?

Most biomass isn’t food—for us

There is another complication. Most of the plant material produced on Earth, even that produced by agriculture, isn’t edible by humans. A grass-covered hillside is producing phytomass. But it’s not producing human food, at least not directly. We can’t eat grass but a cow can. More precisely, ruminants and the extraordinary microbial ecosystem contained within their rumens can. Ruminants consume fibrous plant material humans cannot digest and transform it into foods we can digest—foods providing highly digestible protein with the indispensable amino acids humans require, along with fatty acids, vitamins, minerals, and other nutrients. They can utilize grasslands unsuitable for crop production, as well as forages, crop residues, and by-products from other parts of our agricultural and food systems.

I’ve sometimes called them Ruminant Rumpelstiltskins. They don’t quite spin straw into gold. But transforming human-inedible biomass into nutrient-dense human food is an impressive trick. And it exposes a problem with the way we sometimes think about food-system efficiency.

If we count kilograms of material consumed by an animal without distinguishing between things humans can and cannot eat, are we measuring competition for food?

If we compare kilograms of crude protein without accounting for amino-acid composition, digestibility, and bioavailability, are we measuring nutritional output?

If we compare environmental impact per calorie while treating calories as nutritionally interchangeable, are we measuring the thing we actually care about?

Or are we answering the wrong questions very precisely?

What are we trying to sustain?

During my presentation I suggested turning a familiar sustainability question around.

Instead of beginning with:

How much animal-source food can a sustainable food system tolerate?

begin with:

What food system can sustainably provide the nourishment required for human health?

Only then should we ask how to produce it.

“Can we produce it?” should not logically precede “What do people need?”

That doesn’t make the production question disappear. Quite the opposite. It makes it an obligation.

If metabolic-health science tells us that the foods people require differ from what our current food system is designed to provide, then “we can’t feed the world that way” isn’t the end of the conversation. It’s the beginning of one. We have to figure out how.

That will require agriculture, nutrition, medicine, ecology, food processing, distribution, retail, economics, and policy to talk to one another. And we’ll have to be careful about assumptions moving from one discipline into another disguised as established facts.

Most importantly, we’ll need to agree about what we’re trying to accomplish.

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From edible biomass to nourishment

The history of agriculture is the story of humanity modifying its environments to produce more edible biomass. That achievement made civilization possible. But producing ever more edible biomass cannot be our only objective for the future. Not when societies awash in calories are simultaneously burdened by metabolic disease. Not when essential nutrient inadequacies remain widespread. Not when much of what fills our supermarkets would have been unrecognizable as food to our grandparents. And not when food means more to human beings than its nutrient composition. So perhaps the next chapter should be different:

The future of agriculture must be the story of producing better nourishment.

Which brings us right back to where we started: What is “food”?

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Tomorrow I leave for San Diego and the Symposium for Metabolic Health. On Saturday, I’ll present “The Fat of the Land: Ruminants, Metabolic Health, and the Next Food Revolution.”

The title is an obvious allusion to Vilhjalmur Stefansson’s The Fat of the Land.

But the presentation begins with a much more contemporary objection.

We can’t.

We can’t expect people to eat more animal-source foods.
We can’t produce enough meat for everyone.
We don’t have enough land.
Livestock compete with humans for food.
Ruminants are inefficient.
And even if animal-source foods might improve human health, producing more of them would be environmentally unsustainable.

I’ve heard variations of those arguments for years.

They raise an important question:

What if improving metabolic health requires us to produce and consume more animal-source foods?

Then “we can’t” isn’t a satisfactory answer.

What does it mean to nourish?

Before asking whether agriculture can produce enough food, perhaps we need to ask a more fundamental question:

Enough of what?

We tend to discuss food in terms of calories, kilograms, protein, land use, greenhouse gases, or production efficiency. Those measures can be useful. But none, by itself, tells us whether people are being nourished.

Protein isn’t simply protein. Amino-acid composition, digestibility, and the food matrix matter.

Meat isn’t simply protein. Neither are milk, eggs, or fish. Animal-source foods provide packages of highly-bioavailable essential nutrients.

And fat isn’t simply something that comes along with protein.

That last point takes me back to Stefansson.

During the famous Bellevue experiment of 1928–29, Stefansson and Karsten Anderson demonstrated that humans could remain healthy for a year eating an exclusively meat diet. But there was an important qualification: very lean meat wasn’t enough. They needed fat.

Nearly a century later, that observation raises some interesting questions.

Where are we—and where are we going?

As I’ve prepared this presentation, I’ve been trying to put numbers around a question that is usually treated rhetorically:

Could agriculture actually supply the animal-source foods required by a metabolically healthier population?

The answer depends, of course, on what we assume that population eats.

I’ve modeled current production against several dietary scenarios—not as prescriptions or definitions of a ketogenic diet, but as ways of testing the capacity of the food system.

One result surprised me.

Protein may not be the constraint we assume it is.

Current global animal-source-food production potentially provides high-quality protein for far more people than conventional discussions of livestock efficiency might lead us to believe.

Fat is another matter.

As carbohydrate intake falls, dietary energy has to come from somewhere. That makes the amount and source of dietary fat increasingly important—and raises questions that receive remarkably little attention in discussions about the future of food.

It also makes the ruminant rather interesting.

Ruminant Rumpelstiltskins

Cattle, sheep, goats, and other ruminants possess something we don’t: a rumen and its extraordinary microbial ecosystem.

Those microbes allow ruminants to consume grasses and other forages, crop residues, by-products, and other biomass that humans cannot digest and transform them into foods that we can.

They turn what is nutritionally unavailable to us into highly bioavailable essential nutrients.

And fat.

Not quite spinning straw into gold.

But close enough that I’ve started thinking of them as Ruminant Rumpelstiltskins.

That ability matters because most of Earth’s agricultural land isn’t suitable for growing crops, and enormous quantities of plant biomass produced by agriculture and natural ecosystems aren’t human-edible.

The relevant question therefore isn’t simply:

How much land does livestock use?

Nor is it:

How many calories of feed does it take to produce a calorie of beef?

Those calculations can produce perfectly accurate answers to the wrong questions.

Better questions include:
What resources are being used?
Could humans otherwise eat them?
What nutrients are being produced?
What other functions does the agricultural system provide?

And, most importantly:

What agricultural system best nourishes metabolically healthy human beings while sustaining the ecosystems upon which we depend?

From “We Can’t” to “We Must”

I don’t think ruminants can feed the world by themselves. Nor do I think they need to.

Humanity needs diverse agricultural systems and diverse animal-source foods—ruminant meat and dairy, pork, poultry, eggs, fish and shellfish—integrated with the plant production upon which all heterotrophs ultimately depend.

But I increasingly think we’ve framed the livestock question backward.

We begin with assumptions about what agriculture should produce and then ask people to construct diets from the resulting food supply.

Perhaps we should begin with human physiology.

What does a human being need to be nourished?

Then we can ask what agricultural systems can provide it, for billions of people, while protecting the natural resources upon which future generations will depend.

If restoring metabolic health requires more high-quality animal-source foods—not less—then the challenge facing agriculture isn’t to explain why we can’t produce them.

It’s to determine how we must.

That’s what I’ll be talking about Saturday in San Diego.

And it leads directly to another question I’ve been working on:

What is “food,” anyway?

More on that soon.

Ecosystem services and sustainable food systems are, naturally, topics of interest for many. From my perspective, most considerations of them fall short. In many sustainability discussions, for example, human health is either omitted entirely or assumed rather than examined. When it is discussed, it is usually through the lens of current dietary guidance rather than emerging evidence concerning metabolic health.

Service

Ecosystem services provided via well-managed grazing systems include:

1. Provisioning (Food, fiber, & materials)

2. Regulating (Carbon sequestration, Water regulation, Erosion control, Nutrient cycling, Fire mitigation, & Pest regulation)

3. Supporting (Biodiversity, Soil formation, & Ecosystem productivity)

4. Cultural (Livelihoods, Heritage, Recreation, & Stewardship values)

They’re all critical services, with the Provisioning arguably being the most vital. Every other ecosystem service is important, but none can replace agriculture’s primary responsibility of producing food.

The history of agriculture is the story of humanity modifying its environments to produce more food. We’re the ultimate environmental engineers. Every species modifies its environment to some degree. Humans simply became extraordinarily good at it. This history began long before the classic paleolithic/neolithic boundary. Predatory patterns and practices, and anthropogenic fire, for example, are human interventions that modified landscapes and the fauna that inhabited them. The process of domesticating plants and animals undoubtedly began long before evidence discernible today in fossil evidence, although we’re constantly learning more.

Sustain

First of all, “sustaining” cannot mean “maintaining.” Agricultural scientists and their colleagues from related disciplines are striving to address many challenges that accompany our present agricultural practices. A striving for advancements in a number of often inter-related topics is the mark of true sustainable improvement. It is a ‘wicked’ problem.1

Sustainability should never be an end in itself, although it is frequently treated that way.

We sustain something for a purpose. Ultimately a sustainable food system must be one that can sustainably provide the foods and nutrients required for human health and flourishing. And there can’t be just one food system. There can never be a single globally optimal food system because environments, cultures, resources, and nutritional needs differ.

Humanity’s diet is already overwhelmingly plant-based. Cereals (wheat, rice, and maize (corn) provide most of the world’s calories and crude protein. The challenge facing humanity is therefore not producing more carbohydrate calories. Rather, the challenge is producing the foods that better support our development and function.

Vision

If this diagnosis is correct, what follows? The future of agriculture must be the story of providing better nourishment. Achieving that future will require many things, among them are a Forage Renaissance and a Ruminant Revolution.

Forage Renaissance: Recovering the central role of grasses, legumes, forbs, cover crops, perennial systems, and other forage resources in resilient and productive agricultural landscapes.

Ruminant Revolution: Rediscovering the indispensable role of ruminants in transforming human-inedible resources into nutrient-dense foods that support metabolic health, and human flourishing, while supporting ecosystem function.

August will be a busy month. I plan to follow this post with three more:

• Part 2: What Is Food?

• Part 3: Why There Must Always Be Ruminants

• Part 4: The Missing Pillar of Sustainability

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Thank you for reading!

“Researchers in animal nutrition have many advantages over their counterparts in human nutrition—including the fact that their subjects don’t lie on their food frequency questionnaires!”

Orts. It’s probably not a word you’ll hear outside animal nutrition, but if you’ve conducted on feeding trials, you’ve likely used it without giving it much thought. Like many terms, it describes something ordinary that turns out to have broader significance. In this case, it also provides a fitting introduction to a few important ideas left behind after my recent post, The Tyranny of Crude Protein. Orts are the feed left in the bunk or pan after the animal has finished eating. In nutrition research, they’re not simply discarded. They’re weighed, analyzed, and accounted for in the calculations because they tell us how much the animals actually consumed. Welcome to today’s Ruminati Word for the Day: Orts.

Unlike livestock nutrition studies, human nutrition researchers usually cannot directly measure everything people eat. Instead, many observational studies rely on food frequency questionnaires, in which participants estimate how often they consumed dozens or even hundreds of foods over the previous months or year. Validation studies using objective biomarkers have shown that these reports are subject to substantial systematic error, with participants tending to underreport some foods and over report others. The resulting measurement error is not simply random ‘noise’—it can bias conclusions in predictable ways.1

Researchers in animal nutrition have many advantages over their counterparts in human nutrition—including the fact that their subjects don’t lie on their food frequency questionnaires! Groups of genetically-similar animals can be controlled for periods of time and the amount of feed that they ingest can be known to a high degree of certainty. Typically the nutritive quality of that feed will have been determined analytically. The researchers do not depend upon table values or apps. Depending upon the research questions being asked, actual body composition can be determined through harvest. It’s obviously impossible to perform that kind of rigorous investigation with human beings.

Leftover protein topics

For decades, animal nutrition has evaluated protein based on the amino acids actually available to the animal. Human nutrition has too often evaluated protein based on what was on paper—or what people remembered eating. Bridging those two worlds may improve both nutrition science and public health.

Lost in Translation

I used ChatGPT to double-check what I’d done manually—search the 2020-2025 Dietary Guidelines for Americans (DGA) for the following words, phrases, and acronyms:

• essential amino acids

• indispensable amino acids

• amino acid profiles

• limiting amino acids

• leucine

• lysine

• methionine

• DIAAS

• PDCAAS

• protein quality

• protein digestibility

• amino acid requirements

Zero discussion. Zero. The DGA discussed protein extensively, but they never explained what humans actually require—the indispensable amino acids that protein supplies. The document repeatedly encouraged consumption of “protein foods,” discussed protein almost entirely as grams or as a food group, never distinguished between proteins of different amino acid quality, never introduced the concept of essential/indispensable amino acids, nor explained that humans require essential amino acids, not simply grams of protein.

I subsequently repeated the same search on both the 2025 Dietary Guidelines Advisory Committee Scientific Report and the final 2025–2030 Dietary Guidelines. While the final DGA are now much shorter and recommend protein in grams per kilogram of body weight rather than emphasizing ounce-equivalents, neither document meaningfully discusses indispensable amino acids, DIAAS, protein digestibility, or protein quality.

Dietary Reference Intake (DRI) scientific report (2006, Chapter: Protein and Amino Acids) recognized that human protein requirements are fundamentally requirements for digestible indispensable amino acids, not merely grams of crude protein. Historically, they discussed “reference protein,” amino acid scoring patterns, digestibility, and protein quality in considerably more detail than the DGA.

The DGA simplified that science. They focused on food patterns, food groups, and total protein intake (grams or food-group equivalents), with little or no discussion of indispensable amino acids or protein quality. As stated, the 2020–2025 DGA did not even use the phrase “essential amino acids.”

This simplification had consequences. If you remove the concepts of amino acid composition and digestibility, it becomes much easier for the public to conclude that “an ounce is an ounce” or “all proteins are nutritionally equivalent,” when physiologically they are not.

Why did the public guidance move away from concepts that the scientific literature itself recognized as fundamental to human protein nutrition? I’ll resist the urge to speculate about their motives, but the less attention a dietary framework gives to protein quality, digestibility, and indispensable amino acid requirements, the easier it is to misleadingly portray proteins from diverse food sources as nutritionally interchangeable.

Layers of Footnotes

Even the DRI seems to bury the lede when they mention grams of “reference protein,” When I looked for the definition of reference protein, I found the phrase “high quality protein.” High quality protein, I was informed, is protein from meat, eggs, dairy, and/or seafood. This critical detail was lost in the creation of the Dietary Guidelines—they didn’t mention “reference protein,” either.

Ounce Nonequivalents

The 2020–2025 Dietary Guidelines relied heavily on ounce-equivalents (oz-eq) as the unit for the Protein Foods Group. An ounce-equivalent might be:

• 1 oz lean meat, poultry, or seafood

• 1 egg

• ¼ cup cooked beans

• ½ oz nuts

• 1 tablespoon peanut butter

The purpose is to facilitate meal planning within the USDA Food Patterns. Given the importance of this concept, the following findings reported by Park, et al.2 are striking:

• “The basis for considering these protein food sources to be ‘equivalent’ is unclear.”

• “...these ‘equivalent’ protein food sources do not appear to be equivalent in any respect.”

• “The magnitude of anabolic response was directly related to the EAA [essential amino acids] content of the protein food source.”

• “We conclude that ‘ounce equivalents’ of protein food sources as expressed in the DGAs are not metabolically equivalent...”

• “The current labeling of the ‘ounce-equivalent’ protein food sources in the DGAs is misleading to the consumer and the practitioner and should be modified.”

The 2025 Dietary Guidelines Advisory Committee Scientific Report continued to rely on ounce-equivalents as the foundation of its Protein Foods guidance despite the challenge posed by Park et al. The final 2025–2030 Dietary Guidelines largely moved away from emphasizing ounce-equivalents, but they still did not explain protein quality, indispensable amino acids, or digestibility.

Swine nutritionists formulate diets, sorry, rations using digestible indispensable amino acids because they know that equal grams of crude protein are not nutritionally equivalent. Perhaps it’s time human nutrition policy learned from pig nutrition. Maybe “eating like a pig” would be a good dietary guidance…

There’s still more left in the feed pan than I had room to discuss:

• Animal-source foods in least-cost rations... sorry, diets.

• The role of animal-source protein foods in low- and high-income countries.

• Why protein shouldn’t be treated as a source—or a percentage—of calories.

I’ll put those in the refrigerator for later.

There will be more Ruminati Words of the Week, too. Have a favorite bit of agricultural jargon you’d like to see translated for a broader audience? Let me know in the comments.

One reason was that I was attending the joint meeting of the American Society of Animal Science and the Canadian Society of Animal Science in Madison, Wisconsin, where one seemingly random conversation led to another.

About midway through the meeting, I was talking with Dr. Jay Johnson (University of Missouri) about his fascinating work on the effects of heat stress during pregnancy in sows—not only on the offspring, but even on subsequent generations. I’d only just met him. As our conversation turned toward my long-standing interest in therapeutic carbohydrate reduction and metabolic health, he paused and said, “You really should meet Lance Baumgard.”

Thanks to a quick exchange on social media, we arranged to meet before his award lecture.

I arrived a few minutes early.

One of his slides was already on the screen.

It was about Otto Warburg!

For those interested in metabolic health, Warburg should be a familiar name. Readers familiar with Sam Apple’s excellent biography Ravenous will recognize Warburg as one of the giants of twentieth-century biomedical science. He first described the unusual glucose metabolism of cancer cells and later recognized that activated immune cells also become highly glycolytic. His work helped lay the foundation for what we now call immunometabolism.

I had never before seen Otto Warburg featured in a presentation at an animal science meeting.

It immediately caught my attention.

During our conversation, Dr. Baumgard mentioned that his own skepticism of human nutrition science and policy began after reading Gary Taubes’ classic Science article, The Soft Science of Dietary Fat. That was another unexpected connection.

I’ve suspected for years that many researchers at our land-grant universities are generating knowledge directly relevant to modern metabolic health—even though they may not identify with the metabolic health community, and many in that community are unaware of their work.

The science is often remarkably compatible.

The conversations simply haven’t happened.

Animal scientists studying insulin action, nutrient partitioning, immunometabolism, amino acid metabolism, heat stress, lactation physiology, and developmental programming are asking questions with profound implications for human health.

One of the missions of Grass Based Health has always been to reconnect disciplines that once shared common questions but now too often work in isolation.

Sometimes those bridges begin with research.

Sometimes they begin with a conversation.

This week, I was reminded that some of those bridges already exist.

We simply need to cross them.

Congratulations to both Dr. Jay Johnson and Dr. Lance Baumgard on receiving national ASAS awards this week. It was a pleasure meeting both of them, and I look forward to learning more from their work. I suspect you’ll be hearing much more about the work of Dr. Johnson, Dr. Baumgard, and other animal scientists whose research deserves a broader audience in the metabolic health community.

Biological limits

Liebig’s Law of the Minimum states:

Growth, performance, or productivity is limited not by the total amount of available resources, but by the resource that is in the shortest supply relative to the organism’s needs.

A wooden barrel was used to illustrate this.

The barrel is made up of staves of differing lengths. The effective volume of the barrel, therefore, will be determined by the shortest stave. Increasing the lengths of the other staves won’t allow the barrel to hold more. In the figure above, the short stave is labeled Potassium (The “K” in N-P-K fertilizer analysis, from the German word Kalium). Since potassium is deficient in this example, adding more of the other elements won’t improve yield.

The barrel isn’t limited to plant nutrition.

In this figure it’s used to demonstrate the 1st Limiting Amino Acid—how a deficiency in one essential amino acid (in this case Lysine), will limit the body’s use of the others.

1st Limiting Amino Acid -

The essential amino acid found in the shortest supply relative to the amounts needed for protein synthesis in the body. Four amino acids are most likely to be limiting: lysine, methionine, threonine, tryptophan.

Since protein feeds are typically more expensive and poor utilization will lead to environmental impact, swine nutritionists have been balancing their rations accordingly for almost half a century. Human nutrition has been slower to adopt the same quantitative approach to indispensable amino acid requirements.

I’ve used this model to suggest that impaired insulin regulation may be the “short stave” of public health.1 As I discussed in It SOUNDS Good… many folks focus on the longer staves (usually rather poorly defined) in their attempts to improve public health. The Law of the Minimum suggests that if impaired insulin regulation is today’s limiting factor, restoring normal insulin sensitivity would reveal the next constraint, but we’re a LONG way from that point! Until then focusing on those other factors is unlikely to produce significant improvements in the chronic disease burden and is more likely to delay progress.

There’s another lesson we can learn from this example.

Scientific limits

Justus von Liebig was one of the towering figures of 19th-century chemistry. His significance extends well beyond fertilizer. He helped make organic chemistry a systematic experimental science, developed important methods of chemical analysis, and—perhaps most consequentially—created at Giessen a model for laboratory-based graduate education in chemistry that was copied across Europe and the United States.2

Liebig’s 1840 book Organic Chemistry in Its Application to Agriculture and Physiology was enormously influential. His writings stimulated agricultural experimentation and strongly influenced students who later helped establish agricultural experiment stations and agricultural education in the United States (more about that in the future). He was one of the principal architects of agricultural chemistry and a major intellectual ancestor of modern agricultural science. But he did NOT originate the Law of the Minimum!

The stronger historical evidence points to Carl Sprengel (1787-1859). Sprengel, a German agronomist and agricultural chemist, helped establish the mineral theory of plant nutrition. Sprengel published the essential concept in 1828—twelve years before Liebig’s 1840 book:

If a plant requires twelve substances, it will not thrive if even one is absent, and it will grow poorly if one is not present in the amount the plant’s nature requires.

In 1999 a major historical reassessment published in the Soil Science Society of America Journal concluded that Sprengel’s 1828 paper contained, in essence, the Law of the Minimum a decade before Liebig’s influencial work and recommended recognizing him as a cofounder of agricultural chemistry and calling the principle the Sprengel–Liebig Law of the Minimum.3

Despite this recommendation, the principle is still almost universally known as Liebig’s Law of the Minimum. Liebig expanded and popularized the idea—and got his name attached to it. Science, it turns out, has its own limiting factors. Sometimes one of them is recognition.

What’s more, Liebig apparently didn’t create the barrel analogy either!

Meet Arnold von Dobeneck (1867-1926), another German agricultural scientist and editor-in chief of the Illustrierte Landwirtschaftliche Zeitung (“Illustrated Agricultural Newspaper”), a major German agricultural periodical. The original illustration appeared in the October 1903 issue. It appears to have been unconnected to an article and carried only the caption: “Unsere Minimum-Tonne” (“Our Minimum Barrel” or, more literally, “Our Minimum Vat.”) The illustration itself was unsigned. The historical attribution to Dobeneck rests on his role as responsible editor, his known illustration style, and a 1927 obituary specifically noting the popularity of his depiction of Liebig’s principle of plant nutrition.4 Note the attribution to Liebig!

In other words, even the famous “Liebig barrel” appears not to have been Liebig’s.

Public-health limits

Discovery and recognition are not the same thing. Neither is discovery the same as durable incorporation into scientific understanding. Readers of Gary Taubes5 will recognize this pattern in the history of therapeutic carbohydrate restriction: John Rollo (c. 1750–1809), Claude Bernard (1813–1878), William Harvey (1811–1866), and William Banting (1796–1878). Clinical observation, developing physiological understanding, therapeutic application, and popular communication accumulated across generations. Therapeutic carbohydrate restriction has repeatedly emerged, demonstrated clinical success, faded from mainstream practice, and then re-emerged under new names and new advocates. Science doesn’t always advance in a straight line. Sometimes it advances by forgetting something, rediscovering it, renaming it, and eventually understanding why it worked.

Public health may be suffering from two related failures: we have failed to identify the shortest stave, and we have repeatedly forgotten knowledge that might help us lengthen it.

What if impaired insulin signaling and regulation is the shortest stave in the public-health barrel but we keep lengthening the long staves?

• More healthcare spending.

• More screening.

• More pharmaceuticals.

• More nutrition education based on a dietary model that has failed to restore metabolic health.

Those things may have value. But if they aren’t the limiting factor, lengthening those staves cannot raise the barrel’s capacity beyond the shortest stave. And some inputs supplied beyond their useful range may cease to be merely uneconomical and become harmful.

That is a very agronomic argument.

Rollo published one of the first systematic descriptions of treating diabetes with a diet centered on meat and severely restricting carbohydrate in 1797. Numerous observations demonstrate that reducing dietary carbohydrate can rapidly improve glycemic control and reduce medication requirements in people with impaired glucose metabolism. The modern conversations about therapeutic carbohydrate reduction are not new. Our mechanistic understanding has advanced enormously, but the fundamental observations are NOT new. The lesson has repeatedly been discovered, forgotten, and rediscovered—and often attributed to the latest promoter.

Agronomists know that crops cannot outgrow their shortest stave. Animal nutritionists know that protein quality depends on the first limiting amino acid. Perhaps public health has been trying to increase the capacity of the barrel by lengthening the wrong staves. If impaired insulin sensitivity is today’s limiting factor, then no amount of extending the longer staves can compensate. Identifying the shortest stave may be the first step toward restoring the health of the whole barrel.

Have You Heard of Them?

For more than 160 years, the land-grant university system and its Cooperative Extension Service have helped farmers increase productivity, families improve their quality of life, and communities solve practical problems. From crop production and livestock management to home economics and youth development, Extension has been one of the most successful educational innovations in American history. Based on my experience with communities outside agriculture, its existence is largely unknown.

As America faces an epidemic of obesity, type 2 diabetes, metabolic syndrome, and related chronic diseases, an important question deserves consideration: Could the land-grant system become a national leader in addressing one of our most pressing challenges?

The Land-Grant Vision

The story begins with the Morrill Act of 1862. The Act granted federal lands to states to establish colleges dedicated to “the liberal and practical education of the industrial classes.” Unlike many universities of the era, these institutions were intended to serve ordinary citizens—not just social elites. Agriculture and the mechanical arts were central to the mission, but the broader goal was public service through practical education.

Subsequent legislation expanded this vision: the Hatch Act of 1887 established agricultural experiment stations; the Second Morrill Act of 1890 expanded educational access (including the creation of historically Black land-grant institutions; the Smith-Lever Act of 1914 created Cooperative Extension, linking university expertise directly to local communities; the Equity in Educational Land-Grant Status Act of 1994 added Tribal colleges and institutions to the land-grant institutions (see also the Association of Public & Land-Grant Universities).

Most Americans have never heard of these acts—or indeed the institutions they launched—yet their legacy reaches into every county in the nation. Might they be key to restoring this nation’s health?

Together, these institutions formed a remarkably effective knowledge system:

Communities ⟷ Extension ⟷ Research

Discoveries made in university laboratories and experiment stations were translated into practical guidance delivered through county-based educators. Local problems were identified and answers sought—either through the application of available knowledge or addressed through research.

Since 1914, every generation has presented Cooperative Extension with new practical problems. Today, metabolic disease may be one of the most important.

Cooperative Extension:
America’s Knowledge Network

For generations, Extension agents have been trusted local resources. They’ve helped producers improve resource management, animal nutrition, soil conservation, crop production, and pest control. They taught food preservation, family nutrition, financial management, and youth leadership through programs such as 4-H.

Extension’s mission has always been remarkably broad. Yes, it includes agriculture, but also forestry, natural resources management, home economics, food preservation and food safety, gardening, community development, leadership, and youth development through 4-H, to name a few. The common thread has never agriculture alone. It has been practical education that improved people’s lives.

The model is simple but powerful: Rather than expecting citizens to travel to the university, the university came to them. At its peak, Extension represented perhaps the largest and most effective adult education network ever created. It is an institution literally created to build bridges.

Forty years ago, my professional life began as Oregon State University’s Forage Extension Specialist, a member of the Cooperative Extension and the land-grant university system. That role was dedicated to helping producers understand forage systems, grazing management, ruminant nutrition, and the practical application of agricultural science. Long before I became immersed in metabolic health, I believed deeply in the land-grant mission: conduct good research, translate it into practical knowledge, and deliver it to the people who can use it. It remains one of the greatest educational models ever created and a uniquely American one.

If America already possesses a trusted, research-based educational network with nearly 3,000 local offices, perhaps the question isn’t whether we need a new system to address metabolic disease. Perhaps we should ask whether one of our greatest existing institutions is prepared to take on one of our greatest emerging public health challenges.

Nutrition Became Part of That Mission

Over time, nutrition education became an increasingly important part of Extension’s work, particularly through federally supported programs serving families and communities. Extension educators faithfully carried out that responsibility. They taught the guidance they were charged with communicating, using educational materials that reflected federal nutrition policy and the prevailing professional consensus of the time.

I don’t question their commitment. I don’t question their desire to improve public health. Many of those educators are friends and colleagues whom I respect deeply. But during the nineteen years of studying human nutrition and metabolic health, one lesson has become increasingly clear. Nutrition science continues to evolve. Perhaps more importantly, we’ve begun distinguishing between two very different questions.

What constitutes a generally healthy diet?

and...

What constitutes an effective therapeutic diet for people already living with metabolic disease?

Those are not the same question. The first will likely continue to be debated for many years. The second has become increasingly informed by clinical research.

America already possesses an extraordinary, trusted, county-based infrastructure for translating science into practice.

A Conversation I Haven’t Forgotten

Several years ago, I had a conversation with an Extension administrator that has stayed with me ever since. After discussing metabolic health and therapeutic carbohydrate reduction, he told me that he believed what I was saying. He had seen many of the benefits personally. Then he added something that deserves thoughtful consideration.

Much of Extension’s nutrition programming depends upon federal funding tied to nutrition education. Asking Extension to substantially change its educational approach could place significant programs, positions, and budgets at risk.

I appreciated his honesty. That conversation convinced me that the challenge wasn’t simply scientific. It was educational and institutional as well. Universities, like all organizations, respond to incentives.

Science Doesn’t Stand Still

Over the past several decades, an increasingly robust body of clinical research has demonstrated that therapeutic carbohydrate reduction has been shown to improve glycemic control, reduce insulin requirements, achieve remission of type 2 diabetes in some patients, improve metabolic syndrome, and treat several other manifestations of metabolic dysfunction. That doesn’t mean every person should eat a ketogenic diet. It does mean therapeutic nutrition deserves a place in serious scientific and educational discussions.

Throughout my career—while as faculty and after—I have thought of Extension as moving knowledge between the university and local communities.

The flow has always been bidirectional.

County educators identify problems.

Researchers investigate them.

Extension translates discoveries back to the community.

That same model could now help address one of the greatest practical problems facing those same communities: metabolic disease.

Another Bridge Waiting to Be Built

I have occasionally observed a growing separation between Agriculture & Natural Resources and Family & Consumer Sciences within Extension systems. Both groups were serving the public. Too often, they were serving the public from different perspectives, with too little interaction. I wonder whether the next great opportunity is bringing those perspectives back together.

• Agriculture produces food.

• Nutrition studies food.

• Medicine increasingly recognizes food as therapy.

Those conversations have always belonged together. Extension is uniquely positioned to help reconnect those conversations.

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A New Opportunity

The release of the 2025–2030 Dietary Guidelines creates an opportunity to re-examine how Extension approaches nutrition education. Whether all of the changes in this edition endure into future Guidelines remains to be seen. What is certain is that our scientific understanding of metabolic disease and therapeutic nutrition has continued to advance over the past several decades. Cooperative Extension has always excelled at translating emerging research into practical education. This may be another opportunity to do exactly that. Not to practice medicine or prescribe diets. Not to advocate for one ideology over another, but to help communities understand emerging science. To distinguish between diets intended for general health and diets used therapeutically. To encourage informed conversations rather than reinforce old assumptions.

To build bridges where disciplines have become isolated.

Looking Ahead

One of the most encouraging developments over the past several years has been hearing from friends and former colleagues who have adopted some form of therapeutic carbohydrate reduction themselves. They weren’t persuaded by ideology. They were persuaded by their own health. Improved metabolic health. Better glycemic control. Reduced medications. Improved energy. Better quality of life.

Those personal experiences don’t replace scientific evidence. But they do something equally important—they create curiosity. People who experience meaningful improvements naturally begin asking new questions and looking at the research with fresh eyes.

The land-grant system helped transform American agriculture and rural America. Its next great contribution may be helping reconnect agriculture, nutrition, and medicine. The bridge already exists. We simply need to extend it.

Extension has always existed to help people solve practical problems using the best available knowledge. That mission hasn’t changed. Perhaps the opportunity before us isn’t to reinvent Extension. The land-grant system transformed American agriculture and rural America because it connected research with practice. Today, another connection is waiting to be made:

Agriculture ⟷ Nutrition ⟷ Medicine ⟷ Metabolic health

The chronic diseases now affecting so many Americans are not someone else’s problem. They affect farm families, rural communities, county governments, schools, and businesses. Every Extension office serves people whose lives have been touched by obesity, type 2 diabetes, fatty liver disease, cardiovascular disease, or other manifestations of metabolic dysfunction. Those people include Extension educators themselves.

As I head to Denver, my goal isn’t to convince every Extension educator to recommend ketogenic nutrition. My goal is to encourage thoughtful conversations about therapeutic nutrition, metabolic health, and the growing body of clinical evidence. If Cooperative Extension has always existed to help communities solve practical problems using the best available knowledge, then this conversation belongs in Extension.

After all, bridges are rarely built in a single day. They begin when people on both sides decide the connection is worth making.

Share Grass Based Health

This week, at the American Meat Science Association’s 79th Reciprocal Meat Conference in Amarillo, Texas, I reached another mountain-top moment. Anyone who has spent time in the mountains knows that standing on the summit, however you’ve gotten there, is only a small part of the experience.

There is the planning. Choosing the objective. Studying the route. Gathering the right equipment. Finding the right companions. Preparing for challenges that may arise along the way.

For me, the preparation began years ago—joining the AMSA, attending meetings, making connections, and volunteering to serve on the Program Committee. Last year I proposed a session on meat’s role in metabolic health. The objective was straightforward to state but challenging to accomplish: bring together experts from disciplines beyond the traditional boundaries of meat science to examine the evidence surrounding animal-source foods, metabolic health, and chronic disease.

Then comes the climb. The emails. The phone calls. The recruiting. The scheduling. The pre-event meetings. The uncertainty about unforeseen details and last-minute glitches. Will it all come off as hoped? (see my previous post for details)

Eventually there is the moment when we stand on the summit, taking it all in. The 79th RMC in Amarillo was one of those moments—the vision became reality. Dr. Teresa Davis, Dr. Eric Westman, and Dr. David Harper shared perspectives drawn from decades of research and clinical experience. They each gave informative, engaging presentations and the feedback I’ve received has been very rewarding and encouraging. Several long-time AMSA members told me they had hoped to see metabolic health addressed at RMC for years. Hearing that was especially rewarding. The following day, Dave Harper joined me for a reciprocal session examining one of nutrition’s most persistent controversies: saturated fat.

Thank you to everyone who attended the sessions, asked questions, stopped me in the hallways, and shared encouragement throughout the week. Those conversations were every bit as valuable as the presentations themselves.

I’ve known Eric and Dave for several years, but it was the first time I’d met Teresa. She was already known withing the meat science community, Eric and Dave much less so, and I believe it was the first time she’d met them.

Building bridges.

It was deeply satisfying to see a conversation I believe is urgently needed taking place within this major meat science conference. Agriculture, nutrition, and medicine were not operating in separate silos. For a brief time, they occupied the same space and addressed common questions. That is precisely the kind of conversation I have hoped to encourage for many years. Most importantly for our future, a large number of students, both graduate and undergraduate, attended. Numerous conversations took place throughout the four days of this event.

The view is spectacular, but mountaintops are not where life is lived. Eventually, every climber must descend. The conference ended and we all headed back to our base camps—our respective homes, institutions, professions, and responsibilities.

Which raises the most important question: What did we bring back with us?

A successful session is not measured by applause, attendance, or even the quality of the presentations. Its value is measured by what participants carry home and put into practice.

• Did new relationships form?

• Did assumptions get challenged?

• Did new questions emerge?

• Did someone encounter an idea that changes the direction of their research, teaching, clinical practice, or professional work?

Time will tell, but those are the things that matter. Mountain summits are destinations, but they are also vantage points. They allow us to see landscapes that are difficult to appreciate from below. They reveal connections that may not have been visible during the climb.

One reason we climb mountains is not simply to reach the top. It is to gain perspective. From the summit, valleys that once seemed isolated reveal themselves to be connected. The same has been true throughout my career. Looking across agriculture, animal science, nutrition, and medicine from a higher vantage point, I continue to see connections that are often hidden within individual disciplines.

The real purpose of reaching the summit is not to stay there. It is to return with a broader perspective. As I reflect on the experience in Amarillo, I am grateful for the opportunity to have made the climb with remarkable colleagues and friends. The summit was rewarding. But mountains are climbed so we can return with a broader view. Now comes the descent—and the work that follows.

Saturday I’ll be traveling to Amarillo, Texas, for the 79th Reciprocal Meat Conference (RMC), the annual meeting of the American Meat Science Association (AMSA).

Amarillo sits on the relatively flat southern High Plains. Canyon is slightly more varied because it lies near the eastern edge of the Llano Estacado and serves as the gateway to Palo Duro Canyon. The landscape features plenty of draws, arroyos, and canyons, but relatively few notable bridges compared with places such as Portland, Pittsburgh, or Prague. Amarillo may not require many literal bridges, but I’ll be spending much of the week trying to build a few intellectual ones.

For many readers, “meat science” may sound like a narrow specialty concerned with processing plants, carcass grading, or food technology. In reality, it is a remarkably broad discipline that sits at the intersection of animal agriculture, biology, nutrition, physiology, food science, engineering, economics, and human health.

As someone whose professional journey began in forage agronomy and ruminant nutrition before expanding into human nutrition and metabolic health, I find meat science to be one of the most important—and least understood—disciplines in agriculture.

What Is Meat Science?

At its core, meat science seeks to understand how living muscle becomes food. The discipline encompasses genetics, animal nutrition, growth, physiology, welfare, muscle biology, carcass evaluation, meat quality, food safety, processing, consumer preferences, and nutritional composition.

Many of the leading meat science programs are housed within America’s land-grant universities. Institutions such as Texas A&M, Iowa State, Kansas State, Oklahoma State, Texas Tech, North Dakota State, South Dakota State, Nebraska, Illinois, Purdue, and others have trained generations of scientists who have improved livestock production, food safety, meat quality, and our understanding of animal-source foods.

The field is inherently interdisciplinary. One meat scientist may study muscle fiber development. Another may focus on protein chemistry, food safety, sensory evaluation, lipid oxidation, consumer behavior, or nutritional value. Yet all are ultimately working toward a common objective: How do we produce more and better food from animals?

Why “Reciprocal”?

Even the conference’s name reflects a tradition of bridge-building. Most people outside the profession—and perhaps many within it—have never stopped to ask why it is called the “Reciprocal” Meat Conference. The term dates to the early years of meat science education, when universities took turns hosting the annual meeting. Faculty members, researchers, and students traveled from institution to institution, with each host school reciprocating the hospitality and participation previously received from others. The conference has not been associated with a permanent venue. Instead, it functions as a cooperative exchange among university meat science programs.

The name reflects a tradition of shared scholarship, mutual professional support, rotating responsibility, and the exchange of ideas. In that sense, bridge-building has been part of the conference’s identity from the beginning. My own participation this year reflects a similar spirit of reciprocity—not between universities, but between disciplines. Agriculture has much to learn from medicine and metabolic science, just as medicine has much to learn from agriculture and food production.

The Reciprocal Meat Conference

The Reciprocal Meat Conference has been held annually for nearly eight decades and serves as the principal gathering of the American Meat Science Association.

Researchers, educators, students, veterinarians, processors, producers, and industry leaders gather to discuss the latest developments in meat science and muscle biology. The conference has become one of the premier scientific forums for the animal-source food sector. This year’s meeting—the 79th RMC—will be hosted by West Texas A&M University in Amarillo and Canyon, Texas.

The conference arrives at a critical time. “Protein” is having a “moment” in the marketplace, but meat is more than merely highly bioavailable indispensable amino acids (as essential as they are). It’s a package of essential nutrients. It also contains various saturated fatty acids, which a still perceived as a concern. Questions surrounding sustainability, public health, environmental impacts, animal welfare, food security, dietary guidance, and the role of animal-source foods are increasingly discussed by people far removed from agriculture. Yet the disciplines most directly involved in producing food often remain isolated from the disciplines concerned with human health.

That separation concerns me, and it should concern everyone.

A Century of Meat Judging

This year also marks the centennial of collegiate meat judging.

To many outside agriculture, meat judging sounds like a niche student competition. In reality, it represents an important chapter in the history of food production in the United States. Meat judging emerged from a simple recognition: the quality of meat can vary tremendously, and evaluating carcasses, primal and retail cuts for yield and quality grade was essential for marketing and improving meat production systems. A century ago, educators realized that students needed to understand how muscle, fat, carcass composition, yield, eating quality, fabrication, economics, and consumer preferences fit together. The resulting programs helped create generations of professionals capable of evaluating meat quality.

The decisions made throughout livestock systems ultimately matter because they influence the food available to consumers. Meat judging helped bridge the gap between animal agriculture and the consumer. It linked production to outcomes. I believe we need similar bridge-building today.

Building Bridges

For several years, I have increasingly described my work as bridge-building.

Agriculture, nutrition, medicine, public health, ecology, food systems, and metabolic science too often function as separate intellectual worlds. Each has developed its own language, assumptions, priorities, and professional incentives. Yet all of them ultimately converge on a common question: How do we nourish human beings?

The livestock community frequently discusses sustainability, protein production, environmental impacts, production efficiency and profit. The medical community increasingly discusses obesity, type 2 diabetes, insulin resistance, metabolic syndrome, fatty liver disease, and other chronic diseases. Surprisingly little attention is paid to the connections between them.

Food systems exist to nourish people, in every sense of that word. If our understanding of human nutrition is incomplete, then our assumptions about agricultural priorities may also be incomplete. That realization has increasingly shaped my work.

Meat & Muscle Biology

One of the most valuable resources produced by AMSA is its open-access scientific journal, Meat & Muscle Biology.

The journal publishes research spanning muscle biology, meat quality, food safety, nutrition, sensory science, and emerging technologies. Unlike many scientific journals, its articles are freely available to readers without subscription barriers.

For anyone interested in understanding animal-source foods from a scientific perspective, it is an outstanding resource.

A Kindred Spirit

One reason I continue attending this meat science meeting is that I encounter colleagues asking similar questions. One such “Herdmate” is Professor Eric P. Berg of North Dakota State University, whom I regard as a kindred spirit.

In 2019 Dr. Berg served as guest editor of the Animal Frontiers issue titled Foods of Animal Origin: A Prescription for Global Health,1 a publication that I frequently recommend. The articles it contains examine livestock and animal-source foods through the lens of human nutrition rather than production alone. Collectively, they argue that discussions of sustainability, food systems, and agricultural policy must account for the unique nutritional contributions of meat, milk, eggs, and fish—not merely their environmental footprints. The issue highlights the importance of high-quality protein, indispensable amino acids, and bioavailable micronutrients, particularly for populations most vulnerable to malnutrition, and serves as a reminder that the ultimate purpose of food systems is not simply to produce food, but to nourish people.

Dr. Berg also co-authored, with Professor Hans Stein, of one of my favorite papers: A Salute to PVT TIM HiLL: Indispensable Amino Acids and Global Human Health.2

The paper uses the mnemonic PVT TIM HILL used to learn the indispensable amino acids: Phenylalanine, Valine, Threonine, Tryptophan, Isoleucine, Methionine, Histidine, Leucine, Lysine.

While the title may raise a smile, the paper addresses one of the most important concepts in human nutrition: people do not require “protein” in the abstract. We require specific indispensable amino acids. The authors review the nine indispensable amino acids, their physiological functions, and the consequences of inadequate intake. The paper serves as a reminder that crude protein is not the same as protein quality and that foods with similar protein contents may differ greatly in their ability to meet human nutritional needs. In doing so, it reinforces the importance of amino acid digestibility, protein quality assessment, and the role of animal-source foods in supporting global human health.

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Two Opportunities

This year I will participate in two sessions.

The first is moderating a panel that I organized: Meat & Metabolic Health: Evidence-Based Insights on Nutrition and Disease Prevention. The speakers and their topics are:

• Professor Teresa Davis, (Texas A&M University) - Dietary Protein and Its Role in Metabolic Health

• Dr. Eric Westman, M.D., MHS (Duke University Medical Center) - Role of Animal-Source Foods in the Treatment of Obesity and Chronic Disease

• Dr. David Harper, Ph.D. (University of the Fraser Valley) - Evidence-Based Insights at the Intersection of Meat Consumption, Metabolic Health, and Cancer

The second is co-presenting with Dr. Harper - From “Bad Fat” to Biomarkers: Reframing Saturated Fat, Meat, and Metabolic Risk.

Our objective is to examine how assumptions regarding saturated fat and meat developed, how they influenced public-health recommendations, and how emerging evidence invites a reassessment of long-held beliefs. Both sessions represent significant opportunities to bring contemporary metabolic science into discussions about animal agriculture and food systems.

Looking Forward

A century ago, meat judging helped connect animal agriculture to food quality. Today, another bridge is needed. Agriculture and medicine. Food production and human health. Meat science and metabolic science. Those conversations too often occur in isolation—indeed sometimes opposition—from one another.

The same bridge-building effort that brings metabolic health into meat science today is one I hope to continue bringing into broader discussions of food systems, sustainability, and grassland science—including next year’s centennial International Grassland Congress in Leipzig, Germany. After all, whether we are discussing grasslands, livestock, meat science, essential amino acids, dietary guidance, sustainability, or metabolic health, the central question remains the same:

What does it actually take to nourish a human being?

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Previous Posts

Readers of my recent essay, The Tyranny of Crude Protein, will recognize many of the themes discussed here: protein quality, indispensable amino acids, digestibility, and the distinction between protein on paper and protein for people.

As a forage agronomist, former Extension specialist, longtime member of the American Forage and Grassland Council (AFGC), and someone whose professional life has revolved around grasses, legumes, grazing systems, hay, silage, and livestock nutrition, I should probably have had this article written weeks ago.

Instead, I was traveling, speaking, and thinking about topics that often seem far removed from forages: metabolic health, food systems, public policy, and chronic disease.

Then it struck me.

Those topics aren’t far removed from forages at all.

In many ways, they begin with forages. In fact, one could argue that much of civilization begins with forages.

When most people think about agriculture, they rarely think about forages. They think about food. They think about crops. They think about livestock. They may even think about soil. But few think about the grasses, legumes, and other forage plants that quietly support much of life on Earth.

That is what National Forage Week celebrates.

Forage (n.). Edible parts of plants, other than separated grain, that can provide feed for grazing animals or that can be harvested for feeding. Allen et al., 20111

National Forage Week is organized by the AFGC, an organization that has played a central role in forage education, research, and outreach for decades. AFGC has been one of my professional homes throughout my career. Through decades of membership, committee work, leadership opportunities, and friendships, it connected me with researchers, educators, producers, and industry leaders who share a commitment to the stewardship and utilization of forage resources. I encourage you to see if there’s an affiliate council in your state. Yet for all the work done by them and other forage professionals, most people rarely stop to consider the fundamental role these plants play in their own lives.

Forages occupy a unique position in our food systems. They are the primary means by which sunlight is converted into the biomass that supports grazing animals across vast landscapes. Through photosynthesis, forage plants capture carbon dioxide from the atmosphere, combine it with water and nutrients from the soil, and create the carbohydrates, proteins, and other compounds that sustain ecosystems—both above AND below the soil surface.

Despite its name, Kentucky bluegrass isn’t from Kentucky.

Today’s vast array of forage species and cultivars traces its origins to plants selected from the world’s grasslands. Through centuries of selection and plant breeding, traits such as yield, persistence, forage quality, and pest resistance have been improved. Many of these species have spread far beyond their native ranges—sometimes intentionally, sometimes not. For example, Kentucky bluegrass, Poa pratensis, is native to Europe, Asia, and parts of northern Africa, not to Kentucky and not to North America. It was introduced by European settlers and became particularly associated with the limestone soils and pastures of Kentucky, where it thrived and helped create the state’s famous “Bluegrass Region.”

Only a relatively small portion of Earth’s land surface is suitable for crop production. Much larger areas are too dry, too steep, too rocky, too shallow, or otherwise unsuited for cultivation. Yet these lands can often support forage plants. Ruminant animals—cattle, sheep, goats, buffalo, and others—possess the remarkable ability to convert those forage resources into foods that nourish people. Through their symbiotic relationship with rumen microbes, they can utilize cellulose and other fibrous materials that humans cannot digest.

In this sense, forages are not merely animal feed. They are the foundation of an extraordinary biological partnership that transforms sunlight, grasslands, and microbial fermentation into human food. National Forage Week is also a reminder that forage systems provide benefits beyond food production. Well-managed grasslands can protect soil, improve water infiltration, support biodiversity, cycle nutrients, and store significant amounts of carbon in their soils.

Healthy forage systems contribute to healthy landscapes. Healthy landscapes support healthy livestock. Healthy livestock produce foods that contribute to human health.

Forage may be the most overlooked component of human nutrition.

The world’s edible protein and energy ultimately begin with photosynthesis, but the majority of it can only reach us because ruminants can harvest nutrition from landscapes and biomass that would otherwise produce no food for people.

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The connection between grasslands and public health is rarely discussed, but it may be one of the most important relationships in our food system—especially when many of the nutrients most difficult to obtain from plants alone are supplied through foods produced by grazing animals.

The next time you drive past a pasture or hay field, consider what you’re seeing.

You’re not just looking at grass.

You’re looking at one of humanity’s most important resources.

Happy National Forage Week!

The paper is worth reading because of the breadth of expertise behind it. The author group includes Frédéric Leroy, Ty Beal, Frank Dunshea, Peer Ederer, Michael Lee, Pablo Manzano, Frank Mitloehner, Sara Place, Agustin del Prado, Giuseppe Pulina, Brad Ridoutt, and Jason Rowntree. Collectively, these authors include internationally recognized experts in human nutrition, food science, grazing ecology, greenhouse-gas accounting, life-cycle assessment, animal science, and sustainable livestock systems.1

Their argument is not that livestock systems have no environmental impact. They do. Nor is it that current systems require no improvement. They do. The argument is that public policy becomes distorted when greenhouse gas emissions—especially simplified carbon-equivalent accounting—become the dominant measure by which meat and livestock are judged.

That matters because food systems do not exist merely to minimize emissions. They exist to nourish people.

The paper estimates that all livestock production in the Western nations contributes about 2.6% of total anthropogenic greenhouse gas emissions globally. At the individual level, dietary restriction of animal-source foods may reduce a Western consumer’s total personal carbon footprint by roughly 1–6%, depending on how restrictive and sustained the dietary change is. These figures describe different scales—one global, one personal—but both are substantially smaller than commonly portrayed in public discussions.

The key question is what else is lost, ignored, or miscounted when carbon becomes the mission. Nutrition is an obvious place to start.

Animal-source foods provide dense, bioavailable nutrition: high-quality protein, essential fatty acids, minerals, vitamins, and other compounds that are often harder to obtain from plant-source foods alone. They are especially important for children, pregnant women, older adults, and people already metabolically compromised.

That last category is not small. In the United States, only 6.8% of adults were estimated to have optimal cardiometabolic health in 2017–2018.2 In other words, less-than-optimal cardiometabolic health is nearly universal. A food-system discussion that treats animal-source foods only as emissions sources, while ignoring malnutrition-driven chronic disease, is not doing a full cost-benefit analysis. The costs of poor nutrition must be counted alongside the costs of food production.

Poor public health has costs, too. As Leroy notes in the accompanying discussion, poor public health may itself function as a “carbon multiplier,” increasing the environmental burden associated with chronic disease. Chronic disease carries economic, social, and human costs as well as environmental ones. It requires hospitals, pharmaceuticals, transportation, medical devices, and long-term care. It reduces productivity, strains public finances, burdens families, and diminishes quality of life. If we are willing to count the emissions associated with producing food, we should also be willing to count the consequences of getting human nutrition wrong.

That is the point of resisting carbon tunnel vision.

A serious food-system analysis must include greenhouse gases, but also nutrition, land use, biodiversity, water, soil carbon, livelihoods, regional differences, methane accounting, co-products, and the ability of ruminants to convert non-human-edible biomass into highly nourishing food.

The world is not a spreadsheet. Food policy should not be either.

References

Paper

Leroy, F., et al. 2026. Carbon Tunnel Vision and Sustainable Meat Production in the West: A Disproportionate Focus on Dietary Greenhouse Gas Emissions? Food Science of Animal Resources 46:69. https://doi.org/10.1007/s44463-026-00072-x

Podcast

FarmGate: Is Carbon Tunnel Vision Obscuring Climate Solutions?

Footnotes

Episode #34 (Spotify & Apple) was just released. It’s also on YouTube (for now)

I was a guest on episode #10 but, as Dave explains, that episode is no longer on YouTube (it is still available on Spotify and Apple). We believe a particular topic discussed in that episode triggered its suppression on YouTube, affecting not only that episode but apparently the channel more broadly. Dave ultimately chose to delete the episode—a decision I supported—after which the channel’s normal growth resumed. We intentionally avoided that topic this time. We’ll see if that was enough.

We covered a lot of ground—literally and figuratively! Over three and a half hours we discussed ruminant digestion, protein quality, land use, human-edible feed conversion, metabolic health, animal-source foods, and the role of livestock in sustainable food systems. Segments will be released on his channel.

Ideas We Discussed

• Ruminants primarily convert resources humans cannot eat into foods rich in indispensable amino acids and other essential nutrients in their most bioavailable forms

• Much of the world’s agricultural land is unsuitable for crop production but suitable for grazing.

• Livestock and plant agriculture are necessarily integrated.

• Protein quality matters, not just protein quantity.

• Animal-source foods play important roles in meeting micronutrient requirements.

• Evaluating food systems requires considering both human health and environmental outcomes.

Many of these claims run counter to conventional narratives about livestock, protein, and human nutrition. During the conversation I mentioned a large number of studies, books, databases, and reports. Rather than leave listeners searching for them individually, I’ve assembled them here in roughly the order they arose in the discussion. If I’ve missed something, please let me know and I’ll add it.

Background references

Bonus!

The Tyranny of Crude Protein may be of interest.

I recently gave a presentation via Zoom - Protein on Paper vs. Protein for People (link to a pdf of the PowerPoint slides w/ notes). It was intentionally “diet agnostic” for an audience that’s heavily influenced by the “plant-based” message.

The references below are organized roughly in the order they arose during the conversation.

Ruminants

Church, D. C. 1993. The Ruminant Animal: Digestive Physiology and Nutrition. (textbook)

Krehbiel, C. R. 2014. INVITED REVIEW: Applied nutrition of ruminants: Fermentation and digestive physiology1. The Professional Animal Scientist 30(2):129–139. https://www.sciencedirect.com/science/article/pii/S1080744615301005

Ruminant microbiome and digestion - Cammack, K. M., K. J. Austin, W. R. Lamberson, G. C. Conant, and H. C. Cunningham. 2018. RUMINANT NUTRITION SYMPOSIUM: Tiny but mighty: the role of the rumen microbes in livestock production. J. Anim. Sci. 96(2):752–770. https://doi.org/10.1093/jas/skx053

Beef is a net protein contributor - Baber, J. R., J. E. Sawyer, and T. A. Wickersham. 2018. Estimation of human-edible protein conversion efficiency, net protein contribution, and enteric methane production from beef production in the United States. Translational Animal Science 2(4):439–450. http://dx.doi.org/10.1093/tas/txy086

Nutrients / nutrition

Amber O’Hearn’s 2019 presentation, Measures of Dietary Quality

Indispensable amino acids - Berg, E. P. and H. H. Stein. 2021. A Salute to PVT TIM HiLL: Indispensable Amino Acids and Global Human Health. Meat and Muscle Biology 5(3). https://dx.doi.org/10.22175/mmb.12925

Food supply statistics available from FAOStat https://www.fao.org/faostat/en/#home

Soybean database - https://www.cropcomposition.org

Cooking cereals changes DIAAS value - Han, F., F. Han, Y. Wang, L. Fan, G. Song, X. Chen, P. Jiang, H. Miao, and Y. Han. 2019. Digestible indispensable amino acid scores of nine cooked cereal grains. British Journal of Nutrition 121(1):30–41. https://dx.doi.org/10.1017/s0007114518003033

“A lot to digest” – Berg and Stein. 2021. ibid

National Live Stock and Meat Board. 1933. Ten Lessons on Meat: For use in the classroom. https://babel.hathitrust.org/cgi/pt?id=coo.31924003579491&seq=76

Land use

FAOSTAT Land Use Database - https://www.fao.org/faostat/en/

USDA NRCS Land Capability Classification - https://efotg.sc.egov.usda.gov/references/Delete/2015-11-14/123_land_capability_10232014.pdf

Integrated Crop Livestock Systems

de Moraes, A., et al. 2014. Integrated crop–livestock systems in the Brazilian subtropics. European Journal of Agronomy 57:4–9. https://doi.org/10.1016/j.eja.2013.10.004

Bell, L. W. and A. D. Moore. 2012. Integrated crop–livestock systems in Australian agriculture: Trends, drivers and implications. Agricultural Systems 111:1–12. https://doi.org/10.1016/j.agsy.2012.04.003

Franzluebbers, A. J. 2007. Integrated Crop–Livestock Systems in the Southeastern USA. Agron. J. 99(2):361–372. https://dx.doi.org/10.2134/agronj2006.0076

Freitas, C. M., et al. 2023. System fertilization in the pasture phase enhances productivity in integrated crop–livestock systems. The Journal of Agricultural Science:1–8. https://dx.doi.org/10.1017/s0021859623000606

Feed / Food

Edible portion of NPP & HANPP estimates derived from - Haberl, H., et al. 2007. Quantifying and mapping the human appropriation of net primary production in earth’s terrestrial ecosystems. Proceedings of the National Academy of Sciences 104(31):12942–12947. https://dx.doi.org/10.1073/pnas.0704243104

96% of the feed consumed by all domestic ruminants is not human edible - Mottet, A., et al. 2018. Review: Domestic herbivores and food security: current contribution, trends and challenges for a sustainable development. animal 12(s2):s188–s198. https://dx.doi.org/10.1017/s1751731118002215

86% of the feed consumed by all domestic livestock is not human edible - Mottet, A., et al. 2017. Livestock: On our plates or eating at our table? A new analysis of the feed/food debate. Global Food Security 14:1–8. https://doi.org/10.1016/j.gfs.2017.01.001

FAO. 2010. Draught Animal Power: An overview. FAO Agricultural Engineering Branch, Rome, Italy. https://www.fao.org/fileadmin/user_upload/ags/publications/draugth_ap_overview.pdf

Draft and Manure

Mota-Rojas, D., et al. 2021. The Use of Draught Animals in Rural Labour. Animals 11(9):2683. https://dx.doi.org/10.3390/ani11092683

Rayne, N. and L. Aula. 2020. Livestock Manure and the Impacts on Soil Health: A Review. Soil Systems 4(4):64. https://www.mdpi.com/2571-8789/4/4/64

Leip, A., et al. 2019. The value of manure - Manure as co-product in life cycle assessment. J. Environ. Manage. 241:293–304. https://www.sciencedirect.com/science/article/pii/S0301479719303627?via%3Dihub

Household air pollution - https://www.who.int/news-room/fact-sheets/detail/household-air-pollution-and-health

Cooking with dung - https://energypedia.info/wiki/Cooking_with_Dung

An egg a day / Too little ASF

Iannotti, L. L., et al. 2017a. Eggs in early complementary feeding and child growth: a randomized controlled trial. Pediatrics 140(1). https://doi.org/10.1542/peds.2016-3459

Iannotti, L. L., et al. 2017b. Eggs early in complementary feeding increase choline pathway biomarkers and DHA: a randomized controlled trial in Ecuador. The American journal of clinical nutrition 106(6):1482–1489. https://doi.org/10.3945/ajcn.117.160515

Iannotti, L., et al. 2021. Livestock-derived foods and sustainable healthy diets. https://www.unnutrition.org/wp-content/uploads/Livestock-Paper-EN_WEB.pdf

Leroy, F., et al. 2023. The role of meat in the human diet: evolutionary aspects and nutritional value. Animal Frontiers 13(2):11–18. https://doi.org/10.1093/af/vfac093

Berg, E. P. 2019. Foods of animal origin: a prescription for global health. Animal Frontiers 9(4):3–4. https://doi.org/10.1093/af/vfz036

Blue zones

Blue Zones - https://www.aleph2020.org/search-results?tx_kesearch_pi1%5Bsword%5D=blue%20zone

Thresholds

At least 50% of dietary protein should come from animal source foods - Vieux, F., et al. 2022. Approximately Half of Total Protein Intake by Adults Must be Animal-Based to Meet Nonprotein, Nutrient-Based Recommendations, With Variations Due to Age and Sex. The Journal of Nutrition 152(11):2514–2525. https://dx.doi.org/10.1093/jn/nxac150

<30% of calories from animal source foods, multiple micronutrient deficiencies emerge - Nordhagen, S., et al. 2020. GAIN Discussion Paper Series 5 - The role of animal-source foods in healthy, sustainable, and equitable food systems. https://doi.org/10.36072/dp.5

60-80% of dietary protein from animal source foods - Ridoutt, B., et al. 2025. Protein Source and Micronutrient Adequacy in Australian Adult Diets with Higher Diet Quality Score and Lower Environmental Impacts. Dietetics 4(35). https://dx.doi.org/10.3390/dietetics4030035

Decreasing protein digestibility with increasing plant source - Moughan, P. J. 2021. Population protein intakes and food sustainability indices: The metrics matter. Global Food Security 29:100548. https://dx.doi.org/10.1016/j.gfs.2021.100548

Oysters, Beans & Tortillas

Zinc, Oysters, black beans & corn tortillas - Solomons, N., et al. 1979. Studies on the bioavailability of zinc in man. 2. Absorption of zinc from organic and inorganic sources. Journal of Laboratory and Clinical Medicine 94(2):335–343. https://www.cabidigitallibrary.org/doi/full/10.5555/19791494841

DIAAS

FAO/WHO. 2013. Dietary protein quality evaluation in human nutrition. Report of an FAO Expert Consultation, 31 March–2 April, 2011, Auckland, New Zealand. FAO food and nutrition paper 92. https://www.fao.org/ag/humannutrition/35978-02317b979a686a57aa4593304ffc17f06.pdf

Bailey, H. M. and H. H. Stein. 2019. Can the digestible indispensable amino acid score methodology decrease protein malnutrition. Animal Frontiers 9(4):18–23. https://doi.org/10.1093/af/vfz038

Moughan, P. J. and W. X. J. Lim. 2024. Digestible indispensable amino acid score (DIAAS): 10 years on. Frontiers in Nutrition 11. https://dx.doi.org/10.3389/fnut.2024.1389719

“Equivalents”

Ounce equivalents - Park, S., et al. 2021. Metabolic Evaluation of the Dietary Guidelines’ Ounce Equivalents of Protein Food Sources in Young Adults: A Randomized Controlled Trial. The Journal of Nutrition 151(5):1190–1196. https://dx.doi.org/10.1093/jn/nxaa401

Odds & Ends

Adele’s dissertation - Hite, A. H. 2019. A Material-Discursive Exploration of “Healthy Food” and the Dietary Guidelines for Americans. https://repository.lib.ncsu.edu/server/api/core/bitstreams/28491ba6-8ae5-4f63-82ab-1ef96d32bf50/content

Working Group member David Klurfeld, the evidence supporting the Group 2A classification of red meat was weaker than many public interpretations suggested - Klurfeld, D. M. 2018. What is the role of meat in a healthy diet? Animal Frontiers 8(3):5–10. https://dx.doi.org/10.1093/af/vfy009

Animal-Sourced Foods in Ethical, Sustainable, and Healthy Diets: A dynamic white paper on the role of livestock farming in global agrifood systems and diets, ALEPH2020.org

National Cattlemen’s Beef Association (NCBA) - https://www.ncba.org/

• Listing of state affiliates - https://www.ncba.org/about/affiliates-industry-organizations

Cooperative Extension - https://www.nifa.usda.gov/about-nifa/what-we-do/extension/cooperative-extension-history

• Find extension in your state - https://extension.org/find-cooperative-extension-in-your-state/

Land-grant Universities - https://www.nifa.usda.gov/grants/land-grant-university-website-directory

These are all terms that sound good. In fact, they sound so good that many people assume everyone means the same thing when they use them. But in science, policy, medicine, and agriculture, the value of a concept depends not on how appealing it sounds, but on how clearly it can be defined, measured, and connected to meaningful outcomes.

That’s where the devil is in the details (and the denominator).

Setting this table

I recently attended a gathering focused on food systems, agriculture, sustainability, and human health. Throughout the discussions I was struck by how often participants relied on terms that sounded compelling but proved surprisingly difficult to define.

I listened to presentations on soil health, nutrient density, regenerative agriculture, and human health. During this gathering of investors, entrepreneurs, scientists, and food-system stakeholders I was struck by how often we rely on compelling but poorly-defined terms. Even “the Mediterranean diet” (which I’ve greatly enjoyed!) illustrates the problem. Does it mean the historical diets of Crete in the 1950s, contemporary Spain, southern Italy, a food-frequency questionnaire pattern, or a modern dietary prescription? The term sounds precise but often refers to several different things.

High-Valence

These terms function as what some communication scholars call “high-valence terms” or “motherhood-and-apple-pie concepts.” They’re words that evoke positive emotional responses and broad agreement while often lacking precise, operational definitions. High-valence terms can become coalition-building tools. Investors, researchers, farmers, policymakers, companies, and consumers may all rally around the same language while attaching different meanings, priorities, metrics, and desired outcomes to it. The resulting consensus can be broad but shallow, obscuring important disagreements that eventually resurface when decisions must be made or resources allocated.

Meaningful discussion requires moving from appealing narratives to operational definitions, measurable variables, and ultimately real-world outcomes. What appears to be broad agreement may actually conceal profound differences in definition and intent. Agreement on a term is not the same as agreement on a definition. Agreement on a definition is not the same as agreement on a measurement. Agreement on a measurement is not the same as agreement on an outcome. Scientific and policy discussions often fail when these distinctions are overlooked.

A Chain of Assumptions

Of all the terms discussed during the event, nutrient density particularly caught my attention because it sits at the center of the commonly proposed pathway linking agricultural practices to human health. The argument often proceeds as follows:

1. Regenerative agriculture produces healthy soils.

2. Healthy soils produce nutrient-dense foods.

3. Nutrient-dense foods improve human health.

Each link deserves examination. In this article, I want to focus on the third term in the chain—nutrient density—because it often serves as the bridge between agricultural practices and claims about human health. If the assumed health benefits are not well supported, the preceding links become vulnerable as well. Agricultural practices that may improve soil function, water cycling, biodiversity, resilience, or even food composition could be unfairly judged by whether they deliver health outcomes that were never adequately demonstrated in the first place. A weak link at the end of the chain can cast doubt on every link that came before it.

Definitions determine what we measure. Measurements determine what we reward. And what we reward ultimately shapes agricultural practices, food production, research priorities, investment decisions, and dietary guidance. If the terms are poorly defined, the measurements uncertain, or the relationships weak, we may be building far-reaching conclusions on a foundation of assumptions rather than evidence. Students of nutrition history will recognize the pattern.

Deconstructing Nutrient Density

Nutrient-dense foods sound like a good thing. But what does it actually mean? Nutrient density is not a direct measure of health outcomes, metabolic health, or nutritional adequacy. Rather, it is a constructed metric that embeds assumptions about which nutrients matter, how they should be weighted, and what dietary goals should be prioritized. Every nutrient-density metric contains a denominator. Nutrients per calorie. Nutrients per gram. Nutrients per serving. Change the denominator and you often change the rankings. What appears to be an objective measure of food quality may simply reflect a choice about what should count.1

Nutrient density and nutrient adequacy are not synonymous. Nutrient density evaluates nutrients relative to some denominator (typically calories, weight, or volume). Nutrient adequacy asks whether human nutritional requirements are actually met. Equally important is nutrient bioavailability—the proportion of nutrients that can actually be absorbed and utilized by the body. Two different foods can have similar protein contents while being significantly different in digestible indispensable amino acid contents. A food can score highly on a nutrient-density index yet contribute little to meeting requirements for highly bioavailable protein, vitamin B12, or other nutrients that are difficult to obtain from some dietary patterns. A food can be highly nutrient dense yet fail to contribute substantially to overall nutrient adequacy. A vitamin supplement may be extraordinarily nutrient dense without constituting a complete food.

The 2020–2025 Dietary Guidelines for Americans (DGA), for example, defined “nutrient-dense foods” as those that “provide vitamins, minerals, and other health-promoting components” with “no or little added sugars, saturated fat, and sodium.” They list vegetables, fruits, whole grains, seafood, eggs, beans/peas/lentils, nuts/seeds, fat-free and low-fat dairy, and lean meats and poultry when prepared with little added sugar, saturated fat, and sodium. Because this definition influences nutrition policy, food labeling, dietary guidance, and food-system discussions, its underlying assumptions deserve careful examination.

So the official definition does not merely mean “rich in essential nutrients.” It necessarily reflects policy judgments regarding which dietary characteristics should be rewarded or penalized—low saturated fat, low sodium, low added sugar, calorie-bounded, lean/low-fat forms. The metric is not neutral; it selects features based on a theory of what matters, then treats the resulting score as if it measures dietary quality itself.

The Short Stave

Like the shortest stave in a barrel limits its volume, the most limiting factor determines the outcome. If insulin resistance and chronic hyperinsulinemia are central drivers of obesity, type 2 diabetes, NAFLD, hypertension, cardiovascular disease, and other non-communicable diseases, then dietary quality cannot be assessed solely by micronutrient content. The metabolic response to foods may be as important as their nutrient composition. A food or dietary pattern may score highly on nutrient-density metrics while simultaneously promoting repeated glycemic excursions, chronic hyperinsulinemia, and metabolic dysfunction.

Against an insulin-resistance framework, the key question is not “Does this food contain micronutrients per calorie?” but “What does this dietary pattern do to insulin demand, glycemia, triglycerides, HDL, hepatic fat, blood pressure, inflammation, satiety, and medication dependence?” Reviews identify insulin resistance and compensatory hyperinsulinemia as central features in type 2 diabetes, hypertension, dyslipidemia, cardiovascular disease risk, NAFLD, inflammation, and some cancer-related pathways.

Evidence vs. Assumptions

Intervention evidence raises important questions regarding the assumptions embedded in most contemporary nutrient-density frameworks. In randomized or controlled feeding studies, carbohydrate reduction often improves metabolic syndrome features more than competing approaches. The implication: “nutrient dense” is a policy-defined nutrient-profile term, not a validated health-outcome term. It may be useful as a rough heuristic, but it becomes misleading when used to imply that low-fat, low-saturated-fat, dietary patterns are automatically health-promoting—especially for insulin-resistant people.

What I’m NOT saying

Just to be clear, I am not saying that:

• agricultural practices don’t impact soils and ecosystem function

• soil and ecosystem function isn’t important

• nutrient content of foods does not vary

• nutrients aren’t important

• proper nutrition isn’t fundamental to health

Take Home Point

Among the participants, there was at least some awareness of metabolic health. That is encouraging. What appeared less appreciated were the implications that follow from taking metabolic health seriously. If malnutrition-driven chronic disease is one of the greatest challenges facing modern societies, then it should influence how we think about food, agriculture, sustainability, nutrient density, and even the outcomes we seek from our food systems. I hope those conversations continue to develop.

If metabolic dysfunction is among the defining public-health challenges of our time, then it cannot remain a peripheral consideration in discussions of agriculture, food systems, sustainability, or nutrient density. The outcomes we seek should shape the metrics we use—not the other way around.

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During my years in Extension, forage testing was a routine recommendation for livestock producers. It still is. There are tables of nutrition values available for hay and other feeds, but farmers and ranchers require better information. Why? Because hay—and all plant dry matter—can vary significantly in nutrient content.

A table value for “orchardgrass, boot stage” isn’t sufficient for winter feeding decisions, supplementation, hay purchases, drought planning, predicting animal performance, or economic projections.

Not only does a feed or food of the same type vary in nutritional composition, but different laboratories can provide different values from the same sample due to analytical variation. My start as an Extension professional coincided with a national laboratory certification effort—an attempt to ensure that the same sample submitted to two different analytical laboratories would receive similar results.

As important as laboratory precision is, the sample itself must also be representative of the hay that’s actually going to be fed. You can’t just grab a handful or take a flake from one bale and assume that’s good enough. Proper forage testing begins by defining the forage “lot”—a relatively uniform quantity of forage harvested under comparable conditions.

Different fields, different cuttings, different maturities, rain damage, delayed baling, excess maturity, leaf loss, heating, or storage conditions call all materially alter nutritive value.

Then, using a proper sampling probe, 20 cores are collected from 20 randomly-selected bales. The resulting sample weighs about half a pound, and the entire amount is sent to the certified forage testing laboratory.

The point is simple: Forages vary. Sampling matters. Analytical methods matter. Interpretation matters. Relying only on “book values” is not considered sufficient in animal nutrition. But in human nutrition, it largely is. And that should concern us. Because the variation in nutritive value in plant-source foods is almost entirely ignored in dietary guidelines, food labeling, sustainability conversations, and public health discussions.

What “Protein” Actually Means on a Food Label

When we see “protein” printed on a food label, listed in a nutrient table, or displayed in a nutrition app, it is usually not a direct measurement of true protein. It is an estimate called crude protein.

The concept originates from the Weende Proximate Analysis System developed in Germany in the 1860s. Crude protein is calculated by measuring nitrogen in a food sample and multiplying by 6.25, based on two assumptions:

1. All nitrogen in the sample is contained in protein.

2. All proteins are 16% nitrogen.

Neither assumption is fully correct.

Some nitrogen exists as non-protein nitrogen. Nitrates, for example, contribute nitrogen but do not provide indispensable amino acids for humans. Likewise, proteins vary in nitrogen content depending on their amino acid composition.

Crude protein was historically useful. It was relatively easy to measure. It enabled tremendous advances in animal agriculture and nutrition science. But usefulness should not be confused with precision.

And crude protein becomes especially misleading when we forget an essential biological reality: Humans do not absorb dietary protein as intact protein.

We denature proteins during cooking and digestion, then enzymatically break them down into amino acids and small peptides. Those amino acids—not “protein grams”—are what the body actually absorbs and uses to synthesize enzymes, transport proteins, antibodies, peptide hormones, connective tissue, and muscle proteins like actin and myosin.

The body’s ability to synthesize those proteins depends on having all indispensable amino acids available in sufficient amounts and proportions. And that changes everything. Or it should.

Minimum vs. Optimum

A critical point must be made before proceeding further. Many current protein recommendations were developed to prevent overt deficiency disease and nitrogen loss—not necessarily to optimize metabolic health, healthy aging, recovery, fertility, or preservation of lean mass. Often this minimum is incorrectly treated as the target. The difference could mean a doubling in protein intake (see Phillips, et al., 20161 and Kanter, et al., 20262).

The Rule of the First Limiting Amino Acid

Animal nutrition has understood this concept for decades. Human nutrition still largely ignores it in public conversation.

The classic analogy is Liebig’s Barrel—a wooden rain barrel with staves of unequal height. Water can only fill to the level of the shortest stave. Protein synthesis works similarly.

The first limiting indispensable amino acid determines how effectively the body can utilize all the others.

Globally, lysine is frequently the first limiting amino acid because humanity’s food supply is dominated by cereal grains: wheat, rice, maize (corn), oats, barley, sorghum, and rye. Cereals provide large amounts of calories and crude protein, but relatively poor lysine density and quality.

Leucine becomes particularly important in higher-income countries and aging populations because it appears to function as a trigger for muscle protein synthesis. Roughly 2–3 grams of leucine per meal may be required to maximize muscle protein synthesis in adults, especially older adults.

This matters profoundly for healthy aging, recovery from illness or surgery, maintenance of lean mass, prevention of sarcopenia, and metabolic health.

“All I’m seeing is sarcopenic obesity.”

A physician colleague

Patients may appear “normal weight,” yet have lost substantial lean tissue while accumulating excess adiposity and metabolic dysfunction. That is not merely a “calorie imbalance.” And it may not simply be a “protein deficiency” in the conventional sense either. It may represent chronic insufficiency of digestible indispensable amino acids within diets that appear adequate when measured only as crude protein.

“Just Eat More Plant Protein” Is Not a Serious Answer

At this point someone usually asks: “Can’t people just eat more oats, wheat, rice, or beans to get enough amino acids?” Sometimes. But not always practically. Nutritional adequacy exists within physiological, metabolic, and practical constraints, such as:

• gut capacity

• total caloric load

• carbohydrate burden

• anti-nutrients like phytate

• fiber tolerance

• digestibility losses

• amino acid damage from processing

And these constraints matter even more in children, older adults, or metabolically unhealthy individuals. Processing also matters enormously.

Heat damage, extrusion and other cereal processing reduces utilizable lysine and sulfur-containing amino acid content. Processing often increases glycemic impact without improving amino acid quality.

The nutritional value of “protein” cannot, and should not, be separated from digestibility, amino acid balance, or food matrix effects.

Digestibility Matters More Than We Admit

Historically, protein quality evaluation relied heavily on PDCAAS (Protein Digestibility Corrected Amino Acid Score). In 2013, an FAO expert consultation recommended replacing PDCAAS with DIAAS—Digestible Indispensable Amino Acid Score.3 DIAAS evaluates individual indispensable amino acids, measures digestibility at the ileum, is not artificially capped at 100, and better reflects meal complementation.

Foods with similar crude protein values can differ dramatically in utilizable amino acids. Oats and wheat may show similar “protein” values on labels while differing significantly in digestible lysine, leucine, and DIAAS values.

Foods commonly promoted as “good protein sources” may fail to qualify when digestibility and amino acid balance are properly accounted for (DIAAS = 80 - 100).

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“Equivalent Protein Amounts” Aren’t Equivalent

Dietary guidelines often construct meal patterns around “protein equivalents.” But equivalent in what sense? Previous editions of the Dietary Guidelines for Americans used “ounce equivalents”—amounts of various foods thought to replace one ounce of cooked meat. When researchers finally examined those assumptions, the conclusions were devastating:4

“…the metabolic equivalency of these varied protein food sources has not been established.”

“The basis for considering these protein food sources to be “equivalent” is unclear.”

“…these “equivalent” protein food sources do not appear to be equivalent in any respect.”

That should have triggered far more discussion than it did. Because once digestible indispensable amino acids are considered, many sustainability models, dietary recommendations, and protein comparisons begin to wobble.

Or collapse.

The Global Food Supply Is Already “Plant-Based”

Globally, roughly 85% of calories and approximately two-thirds of crude protein already come from plant-source foods. Cereals are the largest single contributor.

The problem is not that humans are consuming “too much animal protein” globally. The problem is that crude protein accounting hides indispensable amino acid insufficiency.

Research modeling protein adequacy in low-income countries found that crude protein alone suggested adequacy in most of the 103 poorest countries.5 Adjusting for digestibility caused many countries to fall below minimum requirements. Adjusting further for utilizable lysine caused all to fall below adequacy.

Sustainability Metrics Built on Crude Protein Mislead

Food-system comparisons frequently evaluate environmental impact “per kilogram of protein.” But what kind of protein? Crude protein? Digestible protein? Digestible lysine? Functional nourishment? Environmental accounting based on crude protein can dramatically distort comparisons between foods and production systems.

If human nourishment is the goal, then human-relevant nutritional metrics must matter. Otherwise we risk optimizing agricultural systems around nitrogen accounting instead of biological nourishment.

There’s More to Nourishment Than Nutrients

Humans do not eat amino acids. We eat foods. Foods carry social meaning, cultural significance, pleasure, memory, ritual, affordability constraints, and practical realities.

Amino acid adequacy matters. But so do cuisine, tradition, access, economics, digestibility, tolerance, and context.

The point is not to reduce food to laboratory chemistry. The point is to stop pretending that crude protein is an adequate representation of human protein nutrition.

A Simpler Way

Individuals are making decisions based upon inadequate information. But protein nutrition for human beings is a complicated subject, as I hope I’m demonstrating. Perhaps there’s a simpler way which would avoid worrying about these “details.” Quoting from the conclusion of an 2021 paper6 (highly recommended reading!):

The complexity of IAA [Indispensable Amino Acid] mixed meal complements are a lot for the average consumer to mentally digest (pun intended). Even if the IAA contents of these foods were listed on the ingredient label as the FAO (2013) recommended, this would not necessarily be helpful to consumers attempting to create a mixed meal balanced in IAA requirements because food labels do not account for the digestibility of the protein. Furthermore, plant proteins offer an even greater level of complexity owing to the antinutritional factors that are naturally present. Consequently, obtaining a protein balance to meet human amino acid requirements in mixed meals is made much simpler by utilizing muscle foods compared with plant-based sources of protein. (emphasis added)

We Need Better Questions

Instead of asking “How much protein does this food contain?” we should increasingly ask:

• How much digestible indispensable amino acids does it provide?

• Which amino acid is limiting?

• What foods complement it?

• How does processing alter availability?

• Is this adequate for children, seniors, or illness recovery?

• What amount is realistically consumable?

• What metabolic burden accompanies it?

• What is the environmental impact per unit of human nourishment rather than per unit of nitrogen?

Crude protein was an important beginning. But it is no longer the best metric.

And perhaps the greatest tyranny of crude protein is not that it is wrong. It is that it is simple enough to make us think we already understand the problem.

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A brief history

In 1996, I believe, I purchased my Whamdiddle hammer dulcimer from Rick Fogel. How I came to be aware of the hammer dulcimer is perhaps a topic for another post.

Given its ancient beginnings and yet still somewhat obscure status, there’s a number of origin stories and historical narratives. So it’s with some hesitation that I offer the following, knowing that I may be inviting some “Well, ACT-shually” responses. (Beginning with the “Is it ‘hammer’ or ‘hammered’?” controversy. I prefer hammer. I have my reasons.)

The hammer dulcimer belongs to one of the oldest and widest-spread families of stringed instruments. These instruments consist of wires stretched across a resonant soundboard, arranged over bridges. It’s played primarily by striking the strings with small handheld hammers rather than by plucking or bowing them. (Some players DO occasionally pluck, bow, mute, or bend the strings while playing, adding tonal color, sustain, texture, and expressive variety beyond the dulcimer’s characteristic struck sound.) There are many related instruments: the Persian santur, Indian santoor, Chinese yangqin, Hungarian cimbalom, German hackbrett. The English form is the most common in North America (they call it “dulcimer” - not to be confused with the Appalachian dulcimer). Its exact origin is debated, but the ancient Near East or Persia between roughly 500 BCE and 1000 CE seems likely.

The hammered dulcimer arrived in North America with European colonists during the 18th century, probably through multiple immigrant streams. By the late 1700s and early 1800s the hammer dulcimer was clearly established in American folk life, particularly in Pennsylvania, New York, New England, and later the Midwest.1 Among its regional nicknames are ‘the lumberjack’s piano’ and the ‘whamadiddle,’ especially in traditions associated with Michigan, Wisconsin, Minnesota, and Ontario timber camps. It was portable, loud enough for dances, mechanically simple, and capable of both melody and rhythm so it fit camp entertainment culture well.

By the early 1900s hammer dulcimers appeared in Sears and Montgomery Ward catalogs, but several factors were leading to the instrument’s decline in popularity. In the 1920s Henry Ford became deeply interested in preserving what he considered “old-time American music” which briefly revived awareness, but the decline continued. There were, fortunately, regional pockets where the tradition was maintained until the 1960s Folk Revival brought some of the remaining players to wider audiences, resuscitating the instrument.

My links

Rick Fogel and Mick Doherty are my links to this tradition. I met Rick first and he introduced me to the Pacific Northwest hammer dulcimer community. I started taking lessons from Mick shortly after that. Mick became my “musical sponsor,” and I consider them both friends.

In 2000 I founded a hammer dulcimer festival that, following two changes in location and a slight name change, still continues.

Following the ‘03 event at Silver Falls State Park near Salem, Oregon, Mick took me on a search for a better location. We found the Oral Hull Park outside of Sandy, OR. Its a wonderful facility and the event, now called the Hammer Dulcimer Rendezvous, has been there ever since. Over the years the instructors have included most of the finest hammer dulcimer musicians in North America. People come from across the country to attend this unique event and the community that’s formed among them gives the event the feeling of a reunion—a rendezvous, you might say…

A regret

So we finally get to the point of this post (beyond an excuse for not getting the Crude Protein post written)!

Here’s a link to the closing group of tunes from ‘09 instructors’ concert that I got to perform with some of the top hammer dulcimer players. This was a personal highlight. Beginning in 2011 my role in the Rendezvous declined due to a job change. Mick agreed to take the lead. I still attended a few more, but at some point I stopped attending. My excuse included schedule conflicts, but I was neglecting the musical “part” of my life that had developed. I haven’t picked up my hammers for years—so many I can’t recall. I’ve said I wanted to “get back to it,” but took no action until this past week.

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Nourishment

As critical as nutrition is, there’s more to nourishment than “just” nutrition. Some describe humans as “the musical ape.” Daniel Levitin’s book This Is Your Brain on Music and other works should inform us that music can and should play an important part of our lives. I’ve neglected my music and all that it taught me.

Humans require community. I’ve neglected these friendships.

I’ve made a decision to re-engage with my dulcimer and with these people. The first tangible action I’ve taken was attending the ‘26 Hammer Dulcimer Rendezvous. The ‘27 ‘vous will be May 13-16. Ken Kolodner will be there. It’s on my calendar.

Check with me to see how I’m progressing on this decision.

Meanwhile, here’s the closing set from the Saturday evening concert: “Wayfaring Stranger” performed by Brenda Hunter, Patti Amelotte, and Simon Chrisman.

Modern life can encourage us to reduce nourishment to nutrients, health to biomarkers, and productivity to output. But humans have always required more than fuel.

I hope you’re nourishing yourselves.

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Big fish eat little fish

[One of the books I recommend is Lierre Keith’s The Vegetarian Myth: Food, Justice, and Sustainability (US Amazon link). Keith provided key insights that I hope have informed my efforts. This heading is what her medical provider told her at a critical point in her life. Substack won’t let me footnote a header.]

At the most fundamental ecological level, life can be divided into organisms that produce organic matter from inorganic inputs (autotrophs) and organisms that must consume already-living matter or its products (heterotrophs).

Autotrophs are the primary biological reducers of atmospheric carbon dioxide, while heterotrophs primarily obtain energy through oxidation of organic carbon compounds.

As discussed in the last post, the vast majority of the plant growth on land (the terrestrial Net Primary Production) is plant structural biomass, not human food. Likewise, most of the agricultural plant growth (the Human Appropriation of Net Primary Production) is also inedible to humans because it is fibrous, lignified, chemically defended, or otherwise nutritionally inaccessible without microbial, mechanical, thermal, or industrial transformation. This is the ecological opening occupied by ruminants and other herbivores: they convert otherwise human-inaccessible plant biomass—especially perennial grasses, forbs, crop residues, and byproducts—into high-quality human food and other products.

Humans are heterotrophs. We cannot hold our hands up to the sun and get a sweet taste in our mouths (we can’t photosynthesize). Contrary to the pronouncements of Breatharianism, we cannot live without food by subsisting on “prana,” “life force,” sunlight, air, or spiritual energy. While they’re admittedly a fringe group, misperceptions of basic ecological principles, food system fundamentals, and human nutrition are widespread.

Trophic misunderstanding

Ecological concepts can be misapplied. Take trophic levels, for example. Each step of a food chain or food web where energy is transferred from one group of organisms to the next is a trophic level. Some have used this to argue for vegan, vegetarian, and so-called plant-based diets.2 It’s true that most of the energy in the biomass consumed by the primary consumers (herbivores) supports maintenance or is lost as heat or waste (e.g. dung and urine) rather than growth or lactation. It’s also true that a similar loss occurs at each subsequent step. Based on this fundamental principle people frequently argue that humans should, essentially, eat the plants and skip the herbivores. But these arguments frequently ignore the equally fundamental fact that most plant biomass is inedible to humans. They also ignore the fact that the amount that is edible is of significantly lower nutritional quality.

“Protein”

These ecological misunderstandings did not remain confined to academic theory. During the 1970s they increasingly shaped public discussions about food, agriculture, nutrition, and environmental responsibility. Among the most influential examples was Francis Moore Lappé’s Diet for a Small Planet (US Amazon link). It was actually cited in the 1977 U.S. Senate “Dietary Goals” report. Several of its central claims, however, rested upon oversimplified or weakly supported assumptions that were already scientifically contestable at the time of publication. These included treating “protein” largely as a quantitative commodity rather than distinguishing protein quality, digestibility, amino acid balance, and nutrient bioavailability; portraying livestock primarily as competitors with humans for food while giving insufficient attention to non-arable land, forage-based systems, coproduct utilization, and nutrient cycling; reducing the nutritional role of animal-source foods largely to crude protein equivalence. Many of these errors still persist.

[I’ve spoken about protein in human nutrition here and here, and it’s on my list for future posts]. Later advances in nutrition science, developmental biology, and systems ecology further weakened these assumptions, while the author herself subsequently acknowledged that her treatment of protein complementarity had reinforced “misconceptions.” And yet it remains an influential book. [For anyone whose childhood was scarred by it, I apologize for rekindling the unpleasant memories. Mine includes a watery soybean casserole topped with Velveeta cheese…]

“Other that THAT…”

A 2018 evaluation of the United States’ beef systems showed that beef is a net contributor to meeting human protein requirements—they produce more human-edible protein than they consume.3 In those parts of the world where cattle are fed no human edible feed at all, of course, this metric becomes literally incalculable—you can’t divide by 0.

Some, including Lappé, persist by relying on environmental arguments as their justification. For them, let me offer this paper that was just published.4

Take home ideas

Humans cannot eat sunlight.

We cannot digest most of the plant biomass produced on Earth.

We remain dependent upon organisms capable of transforming landscapes, cellulose, atmospheric carbon, minerals, and microbial metabolism into forms we can actually use.

We heterotrophs always will.

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Plants convert sunlight, carbon dioxide, and water into biomass through photosynthesis. The portion of that production that accumulates as plant material is termed Net Primary Production (NPP)—the total biological output of the land. But NPP is not food. It is biomass.

What does the global garden grow?

To answer that, we first need an estimate of how much plant matter is produced each year. This is provided by estimates of NPP. This is the rate at which plants (and other autotrophs) accumulate biomass, after accounting for the carbon they use for their own metabolism. It’s formally expressed as:

NPP = Gross Primary Production − Plant Respiration

Think of it as Earth’s plant biomass production (leaves, stems, roots, and seed), both aquatic and terrestrial. Confining ourselves to the terrestrial portion (roughly equivalent to the aquatic), global estimates place this at approximately 50–60 billion metric tons of carbon (C) per year (≈55 petagrams C per year, Pg C/yr),1 based on ecosystem productivity analyses.2 Note that this is carbon, not organic matter. Plant biomass (dry matter) is typically assumed to be 50% carbon. This includes both unmanaged ecosystems and agricultural systems.

So how much of that is human edible? Less than three quarters? Less than half?

If you guessed any of those you’d be “directionally right,” but far from accurate. The answer is that less than ~4% of terrestrial NPP is directly edible by humans—a far smaller fraction than most people assume—based on syntheses of global biomass production and food system flows. Humans lack the enzymatic capacity to digest cellulose and most structural plant carbohydrates, as described in standard plant physiology and human nutrition texts. In addition, many plants produce defensive compounds that are toxic or reduce digestibility.

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What about agriculture?

What’s agriculture? When did it start? Where did it start?

All good questions and subjects for future posts. Without going into detail now let me just say that, once again, the evidence is richer—and more interesting—than the common narratives. For this discussion let’s define agriculture as humanity modifying its environment to enhance edible biomass production.

NPP includes agricultural plant biomass production. That component is termed Human Appropriation of Net Primary Production (HANPP). It represents approximately 18% of NPP (~11 Pg C/yr), according to global land-use and socio-ecological metabolism analyses.3 A remarkable figure in and of itself. But how much of HANPP is human edible?

Less than 14%.

That’s roughly four times the edible fraction provided by unmanaged ecosystems, but more than 86% of the biomass produced as a result of humanity’s agricultural activities is NOT human edible unless it’s first “upcycled” through livestock. Ruminants are the primary biological mechanism by which this inedible biomass becomes human food, other products, and services.

The constraint is not how much plants produce—it is how little of that production we can actually use. Future posts will examine nitrogen fixation, photosynthesis, forages, grasslands, and ruminants.

Further Reading

Haberl, H., et al. (2007). Quantifying and mapping the human appropriation of net primary production in Earth’s terrestrial ecosystems. Proceedings of the National Academy of Sciences. https://doi.org/10.1073/pnas.0704243104

Krausmann, F., et al. (2013). Global human appropriation of net primary production doubled in the 20th century. Proceedings of the National Academy of Sciences. https://doi.org/10.1073/pnas.121134911

Field, C. B., et al. (1998). Primary production of the biosphere: integrating terrestrial and oceanic components. Science. https://doi.org/10.1126/science.281.5374.237

Smil, V. (2013). Harvesting the Biosphere: What We Have Taken from Nature. MIT Press. https://mitpress.mit.edu/9780262528276/harvesting-the-biosphere/ & US Amazon

FAO (Food and Agriculture Organization of the United Nations). FAOSTAT Database https://www.fao.org/faostat/en/#home

Imagine the surface of the Earth as an apple.

Now cut the apple in half.

Then cut one of the halves in half.

Consider one of the quarters. It represents all terrestrial systems: cropland; rangeland/grassland; forest; deserts, mountains, ice, and urban. Now cut that quarter in half.

One of the resulting eighths represents the biologically productive land, essentially the Earth’s agricultural land.

Now cut one of the eighths in half, and then one of the sixteenths in half.

One of the 1/32 slices plus the other sixteenth slice represent the grasslands, savannas, shrublands, and some marginal pasture. It’s agricultural land, but it’s not arable land.

The other 1/32 slice represents arable land—land capable of being cultivated for crops (based on soil, slope, climate, drainage). It’s a portion of the Earth’s agricultural land. Cropland is land currently used (or recently used) to grow crops, a portion of the arable land.

Now cut the peel off that 1/32 piece. That represents the soil supporting humanity’s crop production systems and thus all of humanity.

This is one way to visualize something that is otherwise difficult to grasp, but must be considered in food systems and sustainability discussions. Agricultural land and arable land are not the same. There’s not a lot of either and their soils are under threat, further reducing these essential resources.

Soil

Soil is the natural, dynamic body at the Earth’s surface, composed of mineral particles, organic matter, water, air, and living organisms. Soil formation is a process of driven by the interactions of multiple factors—climate × organisms × relief × parent material × time. Soil functions as a medium for plant growth, water regulation, nutrient cycling, habitat, and an engineering substrate. Pedology is the scientific study of soils in their natural environment, focusing on soil formation (pedogenesis), morphology, classification, and mapping.

Land

“Soil” and “land” are not synonymous. Soil is a material and biological medium. Land is an integrated system of soil, climate, topography (slope, aspect, elevation), hydrology (drainage, water availability), vegetation, human infrastructure and use. The USDA Land Capability Classification system groups land based on its limitations for sustained cultivation (primarily row cropping). It is not a soil taxonomy—it’s a use/management classification. There are 8 classes (I–VIII):

Class I (~3% of Continental US) - have slight limitations that restrict their use.

Class II (~7%) - have moderate limitations that restrict the choice of plants or that require moderate conservation practices.

Class III (~8%) - have severe limitations that restrict the choice of plants or that require special conservation practices, or both.

Class IV (~8%) - have very severe limitations that restrict the choice of plants or that require very careful management, or both.

Class V (~2%) - are subject to little or no erosion but have other limitations, impractical to remove, that restrict their use mainly to pasture, rangeland, forestland, or wildlife habitat.

Class VI (~14%) - have severe limitations that make them generally unsuitable for cultivation and that restrict their use mainly to pasture, rangeland, forestland, or wildlife habitat.

Class VII (~20%) - soils have very severe limitations that make them unsuitable for cultivation and that restrict their use mainly to grazing, forestland, or wildlife habitat.

Class VIII (~38%) - soils and miscellaneous areas have limitations that preclude commercial plant production and that restrict their use to recreational purposes, wildlife habitat, watershed, or esthetic purposes.

Classes I–IV are considered “arable,” V–VIII are “non-arable” (in a conventional cropping sense). Only one quarter of U.S. land is considered arable, or suitable for sustained cropping. The remainder is inherently better suited to grazing, forestry, or non-food uses. Arguments about land use for livestock vs. crops that fail to account for these fundamental facts are, at best, misguided.

While the United States ranks among the top five countries in total arable land, the percentage of the total land area that’s arable places it the middle of nations (16.7% vs global average of 14.3%). At least three quarters of global arable land has already been converted into crop production. The remaining arable land is largely the remainder of the world’s highly-endangered grassland & savanna biomes. Converting them to cropland (the historical pattern) would come with significant ecological and economic costs.

As precious as this resource is, it is severely threatened. The U.S. has lost ~1/3 of its topsoil since settlement due to nutrient depletion, water and wind erosion. While losses have been reduced from historical peaks, even today ~28% of U.S. cropland erodes above “tolerable” rates. In addition, since the early 1980s the U.S. has converted ~30–40 million acres (~12-16 million hectares) of rural land to developed uses, including, housing (suburban/exurban expansion), commercial/industrial sites, and transportation infrastructure. A large share of this land was prime or productive farmland (Classes I–II disproportionately affected) and represents a permanent loss.

Globally about a third of global arable land has been degraded or lost since 1970 due largely to erosion & physical degradation (approximately two thirds of total loss/degradation), chemical degradation (salinity, nutrient depletion/toxicity, ~15%), urban / industrial conversion (~12%), and pollution.

Arguments against ruminant animal production fail when these realities are considered. The replacement of animal source foods with plant source foods would require greater production from an already-strained resource. The food system of the 21st Century won’t be either-or—plant or animal. Livestock are and will remain essential components. In addition, forage/grazing systems of some kind (e.g. integrated cropping livestock systems, cover cropping, conservation practices, crop-forage rotations, perennial forages) are demonstrated best-practices for the vast majority of our arable lands. Ruminant (or other herbivore) systems is the only wise agricultural use of the majority of our agricultural land that is not potentially arable.

Conclusion

The apple analogy is useful—but incomplete. It shows us how little of the Earth can be cropped, and how thin the soil is that supports it. What it does not show is everything else.

Most of the land on Earth is not arable. But that does not mean it is unproductive. It simply means it cannot be farmed with a plow.

When we fail to distinguish between soil and land, or between arable and agricultural land, we reduce a complex system to a single measure—and in doing so, we draw the wrong conclusions about how that land should be used.

The real task is not to expand that small slice of cropland, nor to imagine that all food must come from it. It is to align our use of land with its capabilities, recognizing that different landscapes support different forms of production.

Our soils are precious—but understanding the land they sit within may be even more important.

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Just last week I learned that the popular story about lemmings—mass, suicidal migrations where they deliberately jump off cliffs—is a myth.

The myth was cemented by the 1958 Disney documentary White Wilderness. In that film, scenes appeared to show lemmings plunging into the sea in large numbers. But the footage was staged. Lemmings were reportedly transported and physically driven off a cliff for the shot. The narration framed this as natural “suicidal instinct,” which is biologically false. Population booms and migrations do occur, but lemmings are not herd animals and there is no coordinated migration. Accidental drownings can occur, but this not evidence of intentional “suicide” behavior or “group-think.”

This film obviously had a cultural impact, embedding the idea in popular consciousness. In everyday language, the word “lemming” is used metaphorically to describe a person who follows a crowd without independent thinking—a usage based on this widespread but inaccurate myth that lemmings mindlessly follow each other to their deaths.

I found the fact that this myth is the result of a staged nature “documentary,” for Disney no less, particularly striking. It reminded me of the phrase “Zombie Myths” - “ideas with high memetic fitness despite empirical refutation.” I think I got the phrase from Dr. Michael Eades. I did some quick research to find others:

“Alpha wolf” dominance hierarchies are natural - Popularized by early captive studies and David Mech’s early work (which he later corrected). Reality: wild packs are family units; “alphas” are simply breeding parents.

Humans use only 10% of their brains - No neuroimaging or lesion data support this. Reality: most brain regions have identifiable functions; global under use would be neurologically catastrophic.

Dietary fat (especially saturated fat) is the primary cause of heart disease - Rooted in mid-20th-century epidemiology (e.g., Ancel Keys). Reality: cardiovascular risk is multifactorial; metabolic context (insulin resistance, lipoprotein subfractions, inflammation) is critical.

“A calorie is a calorie” (metabolic equivalence) - Thermodynamically true, physiologically incomplete. Reality: macronutrients differ in hormonal effects, satiety signaling, and partitioning (e.g., insulin dynamics).

Breakfast is the “most important meal of the day” - Originates partly from marketing by Kellogg’s. Reality: controlled trials show mixed outcomes; benefits depend on individual metabolic context and eating pattern.

Livestock are net protein/food “inefficient” because of feed conversion ratios - Often ignores non-human-edible biomass. Reality: ruminants convert cellulose and byproducts into high-quality protein and fat; human-edible feed conversion (heFCE) can be >1 in well-designed systems.

Methane from cattle is equivalent to fossil CO₂ in warming impact - Conflates flow gas with stock gas dynamics. Reality: methane is short-lived; metrics like GWP* better reflect its warming behavior versus cumulative CO₂.

Medieval people believed the Earth was flat - Popularized in the 19th century (e.g., A History of the Life and Voyages of Christopher Columbus by Washington Irving). Reality: educated Europeans since antiquity accepted a spherical Earth.

Vikings wore horned helmets - 19th-century artistic invention (notably by Carl Emil Doepler for Richard Wagner’s operas). Reality: no archaeological evidence for horned battle helmets.

Water drains “clockwise vs. counterclockwise” depending on hemisphere - Misapplication of the Coriolis effect. Reality: in small systems (sinks, toilets), initial conditions dominate; Coriolis is negligible.

You must drink “8 glasses of water a day” - No universal physiological requirement at that exact level. Reality: hydration needs vary with diet, climate, activity; thirst and urine concentration are adequate guides for most people.

The “Thrifty Gene” Hypothesis and the Dietary Cholesterol Drives Cardiovascular Disease Zombie Myths should not be neglected.

Why do these “zombies” persist?

• Narrative simplicity: single-cause stories out-compete multivariate explanations.

• Institutional inertia: once embedded in curricula/policy, reversal is slow.

• Commercial reinforcement: alignment with product marketing (e.g., breakfast cereals).

• Early authoritative endorsement: initial publication by credible figures creates anchoring.

• Cognitive biases: confirmation bias, availability heuristic, and repetition (“illusory truth effect”).

Your suggestions for the Zombie Myth List are welcome!