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#368 ‒ The protein debate: optimal intake, limitations of the RDA, whether high-protein intake is harmful, and how to think about processed foods | David Allison, Ph.D. - The Peter Attia Drive | Wave AI Podcast Notes

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#368 ‒ The protein debate: optimal intake, limitations of the RDA, whether high-protein intake is harmful, and how to think about processed foods | David Allison, Ph.D.

The Peter Attia Drive

Mon Oct 13 2025

David Allison is a world-renowned scientist and award-winning scientific writer who has spent more than two decades at the forefront of obesity research. In this episode, David joins for his third appearance on The Drive to bring clarity to one of the...

Summary

The Peter Attia Drive — Episode #368

The Protein Debate: Optimal Intake, RDA Limitations, Is High-Protein Harmful, & Processed Food Logic
Guest: David Allison, PhD
Release Date: October 13, 2025

Episode Overview

This episode is a deep-dive into the science and controversies surrounding dietary protein with Dr. David Allison, a leading obesity and nutrition researcher. Dr. Peter Attia and Dr. Allison critically examine the historical cycles of demonizing macronutrients, scrutinize the origins and appropriateness of the protein RDA, discuss whether high protein intake is harmful, and dissect processed foods and public health strategies. Their approach emphasizes evidence over ideology, transparency about conflicts, and the limits of nutrition science. This is Part 1 of a two-part protein series.

Main Themes and Discussion Points

1. The Cycle of Nutritional Demonization

[04:43]

Macronutrient focus has shifted over time: fat → carbs → now protein.
Dietary debates recur as "villain" and "hero" foods rotate.
Dr. Allison:
“There’s always that group that sees other people having fun or making money, and... that upsets them... You’re not being prudent, you’re not taking the natural course... So we’re going to try and pooh-pooh it.” ([06:05])

2. Origins and Misunderstandings of the Protein RDA (Recommended Dietary Allowance)

[06:34] — [13:31]

The 0.8g/kg figure is based on nitrogen balance studies in sedentary, lean young people.
Origins: Meant to prevent deficiency, not optimize health/performance.
Dr. Attia:
“You have to look at the population that is studied and ask the question, how do I differ from that population?” ([11:09])
Dr. Allison:
“No one ever proved … that [the RDA] was the best amount or the upper limit... it’s just what was found to be compatible with survival.” ([07:57])

3. Transparency, Conflicts of Interest, and Scientific Trustworthiness

[13:31] — [16:47]

Both Peter and David disclose their advisory roles with a protein bar company.
True trustworthiness in science comes from transparency in data, methods, and logic, not lack of financial interest.
Dr. Allison:
“In science, three things matter: the data, the methods, and the logic… everything else is tangential.” ([14:21])

4. Why Nutrition Science is Challenging: Methodological & Social Issues

[18:31] — [24:25]

It's hard to conduct rigorous, long-term, controlled studies in nutrition.
Emotional and ideological stakes run high.
Studies are often confounded, underpowered, or rely on surrogates (e.g., cell/mouse models).
The crossover vs. parallel trial debate: statistical efficiency vs. risk of "carryover" effects.

5. Optimal Protein Intake: What Does the Evidence Actually Show?

[30:29] — [37:47]

The RDA is likely the minimum, not optimal, and almost no one should aim for just the RDA.
Higher protein intakes (1.2–2.0g/kg, even up to nearly 1g/lb) are likely beneficial for nearly everyone, especially those aiming to prevent sarcopenia, heal, or perform.
No strong evidence of harm at these higher levels for healthy individuals.
Dr. Allison:
“With rare exceptions, the answer [to who should eat just the RDA] is probably no one.” ([37:00])
Dr. Attia:
“It’s hard for me to imagine... one of my patients who doesn’t need to, at a minimum, work hard to maintain their muscle mass.” ([36:07])

6. Is High Protein Harmful? The Elusive Evidence

[38:49] — [46:26]

Dr. Allison issued a challenge: Show human intervention studies linking high protein intake to harm; no one could provide any.
ICU-level trial (TPN in very sick patients): no observed benefit or harm from higher protein; not generalizable to healthy populations.
Mouse/epidemiological data often conflated, but not definitive.
“Show me the data.”—Dr. Allison's mantra ([38:49])
Biological harm at higher protein doses lacks robust evidence; precautionary calls are not data-driven.

7. The Problem with Nutrition Studies: Underfunding and Weak Data

[48:20] — [51:33]

Nutrition RCTs have tiny sample sizes compared to pharma trials, due to lack of patents/economic incentives.
Most nutrition researchers patchwork funding from industry + government.
Observational studies dominate but can't answer causality questions—editorial and methodological biases abound.
Dr. Allison:
“If you added up all industry-sponsored nutrition outcome research, I’d be surprised if it exceeds a billion dollars.” ([51:48])

8. Epidemiology & Bias: Why Nutrition Advice is So Confusing

[56:24] — [65:02]

Confounding by socioeconomic status, measurement error, selection bias, and researcher bias are endemic.
Dr. Allison:
“Protein intake is highly confounded with social class as well as type of protein intake.” ([65:02])
No compelling epidemiologic evidence that higher protein intakes are harmful or beneficial—studies point both ways and are inconclusive.

9. Verdict and Practical Guidance: What Should You Actually Do?

[69:34] — [72:24]

High-protein intakes (1.6–2.0g/kg/d, or nearly 1g/lb) are advisable for most people wanting to thrive, not just survive.
The evidence for harm is scant; risk lies more in displacement of other nutrients, economics, and potentially adherence, not toxicity.
Dr. Allison:
“I think you and I are largely aligned… if you want to thrive… aim for ~2g/kg/day, spaced out throughout the day.” ([72:24])
Protein needs should be based on goals (muscle, performance, aging), not arbitrary population averages from 80 years ago.

10. Processed & Ultra-Processed Foods: Demon, Heuristic, or Distraction?

[76:26] — [96:15]

Nova classification (processed/ultra-processed) is popular but highly debated and somewhat arbitrary.
“Processing” is not intrinsically harmful—cheese, wine, even cut fruit are processed.
Ultra-processed demonization provides a target for social change, but evidence is nuanced: the core problem is often caloric overconsumption, not processing per se.
Best use: as a rough heuristic for the general public, but not as a causal principle.
Dr. Allison:
“All categories are social constructs… It’s not the ancestry [of a food] but the molecules and their structure that matter.” ([82:45], [87:53])
The “periphery of the grocery store” rule is a useful heuristic, but not a law of nutrition.

11. Why Hasn’t Public Health Solved Obesity? Pharma vs. Policy vs. Social Change

[96:15] — [107:57]

Individual heuristics are helpful but rarely scalable to population health.
Public health efforts (menus, school programs) have limited/short-lived effects; unlike tobacco, food cannot be abstained from.
Lasting solutions may require radically different strategies: broad social/economic change or, more likely, medical interventions (e.g., GLP-1 drugs, bariatric surgery).
Dr. Allison:
“It’s painful, but after 50 years... no, I just don’t think [public health] interventions have manifestly meaningful effects [on obesity].” ([98:23])
Future may see widespread use of anti-obesity medications as a public health solution.

Notable Quotes & Memorable Moments

“No one ever proved, demonstrated, or I think, even claimed that [the RDA] was the best amount… it was just what was found to be compatible with survival.” —David Allison ([07:57])
“In science, three things matter: the data, the methods, and the logic… everything else is tangential.” —David Allison ([14:21])
“It’s hard for me to imagine... one of my patients who doesn’t need to, at a minimum, work hard to maintain their muscle mass.” —Peter Attia ([36:07])
“With rare exceptions, the answer [to who should eat just the RDA] is probably no one.” —David Allison ([37:00])
“Show me the data.” —David Allison ([38:49])
“All categories are social constructs… It’s not the ancestry [of a food] but the molecules and their structure that matter.” —David Allison ([82:45], [87:53])
“The RDA is likely the minimum, not optimal, and almost no one should aim for just the RDA.” —Paraphrase ([30:29]-[37:00])
“Public health has not been able to move this needle [on obesity/metabolic health].” —David Allison ([98:23])

Timestamps of Key Segments

| Time | Segment | |-----------|------------------------------------------------------------------------------------| | 04:43 | Historical demonization of macronutrients | | 07:28 | Origins of the 0.8g/kg protein RDA | | 13:31 | Conflicts of interest and scientific trust | | 18:31 | Why nutrition science is methodologically hard | | 30:29 | Is the RDA sufficient? What is optimal protein intake? | | 38:49 | Allison issues a data challenge: evidence for harm from high protein | | 48:20 | Underfunding and poor sample sizes in nutrition vs pharma trials | | 56:24 | Epidemiology, confounding, and why population studies mislead | | 65:02 | What can we say about protein, cancer, and cardiovascular disease? | | 69:34 | Practical protein advice for patients and the public | | 76:26 | Processed and ultra-processed foods: definitions and logic | | 82:45 | Why "ultra-processed" isn’t a meaningful scientific category | | 96:15 | (Limits of) Public health interventions for obesity/metabolic health | | 98:23 | Rethinking policy: have 50 years of public health efforts solved obesity? | | 107:57 | Future outlook: drugs vs. policy, and closing thoughts |

Flow & Tone

The exchange is rigorous, nuanced, and scientifically literate, with both Peter and David sharing an aversion to dogma, calls for data over ideology, and a sometimes dry wit. They disclose conflicts transparently, are unafraid to critique their own field, and use analogies from math, economics, and culture to ground the discussion. The underlying tone is skeptical but pragmatic, focusing on what can be responsibly recommended—not what’s popular or ideologically satisfying.

For Listeners

Takeaways:

Almost no one (aside from rare exceptions) should limit themselves to the protein RDA—higher intakes are safe and likely beneficial for health, performance, and longevity goals.
Concerns about "high" protein causing health problems in healthy people are not supported by intervention data.
Observational nutrition science is riddled with bias; trial funding is a structural issue.
Processed/ultra-processed food categories are more helpful as layman heuristics than scientific categories.
Public health approaches to obesity/metabolic health have largely failed; pharma may be the next “public health”.

Recommended for:
Anyone confused about protein needs, fed up with nutrition dogma, or curious about how scientific advice is—sometimes shakily—constructed.

End of Episode Summary

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Transcript

A (0:11)

Hey everyone.

B (0:11)

Welcome to the Drive Podcast. I'm your host Peter Attia. This podcast, my website and my weekly newsletter all focus on the goal of translating the science of longevity into something accessible for everyone. Our goal is to provide the best content in health and wellness and we've established a great team of analysts to make this happen. It is extremely important important to me to provide all of this content without relying on paid ads to do this. Our work is made entirely possible by our members and in return we offer exclusive member only content and benefits above and beyond what is available for free. If you want to take your knowledge of this space to the next level, it's our goal to ensure members get back much more than the price of a subscription. If you want to learn more about the benefits of our premium membership, head over to peterattiamd.com subscribe my guest this.

A (1:05)

Week is David Allison.

B (1:06)

David, returning for his third conversation on the Drive is a world renowned scientist and award winning scientific writer who has been at the forefront of obesity research for the last 20 years and is currently the Director of the Children's Nutrition Research center at Baylor College of Medicine. I wanted to have David on because protein has become one of the most contentious and confusing topics in nutrition today. What was once a fairly straightforward subject has now turned into a debate full of conflicting claims, dogma, unnecessary controversy and a whole lot of name calling. David brings both a deep understanding of the science and a clear eyed perspective on how to separate evidence from opinion. This is part one of a two part deep dive on protein and next week I'll be joined by Rhonda Patrick for part two, after which we'll put this protein discussion to rest once and for all. In this episode we discuss the historical cycle of demonizing macronutrients and why protein has recently become the focus the origins and limitations for the RDA for protein and what the evidence suggests about optimal intake for health, longevity and performance Conflicts of interest in nutrition science and why transparency around data, methods and logic matter much more than funding sources the challenges of conducting high quality nutrition studies, including the debate over crossover designs, the limits of epidemiology and the underfunding of rigorous trials compared to pharmaceutical trials what the evidence really says about higher protein intake, muscle protein synthesis and whether concerns about harm are supported by actual data how to think about processed and ultra processed foods including definitions, heuristics and and the question of whether they're inherently harmful or simply a convenient villain and finally, the difficulty of tackling obesity through public health, the limits of current approaches and whether future solutions may rely more on drugs like GLP1 agonists or broader societal changes. So without further delay, please enjoy my conversation with David.

C (7:57)

Right. And at each of those sittings, you probably want to hit about 30. I emphasize that word about. It's not like there's some mathematical proof that there's some hard threshold, and certainly not for you, who is 20% bigger than me, that your hard threshold will be the same as my hard threshold, but in the neighborhood of 30. Right off the bat, if you follow that advice, you'd need to be having double that amount of protein, and you'd have to have it distributed differently. And if you haven't distributed the way you currently did, it'd be more than double. So I think there are a lot of people who disagree with that. The history is people at some point recognized that we needed protein to live. The key indicator of that was nitrogen. And people looked at nitrogen balance. How much did you take in? How much did you excrete? And they found that people could achieve nitrogen balance, or at least sort of ordinary, normal people of the time at about that level. No one ever proved, demonstrated, or I think, even claimed that that was the best amount or the upper limit, or it was just that's probably enough to maintain nitrogen balance, which probably means it's compatible with survival. And if you think about the early days, that was pretty important. Europe couldn't reliably feed its population until two things were entered into Europe. One was guano, bat poop, fertilizer, and the other was potatoes. And when after the Columbus hit Hispaniola, and eventually what came back was, among other things, guano and potatoes, suddenly Europe could feed its population. But it took a while for the potatoes to catch on. Louis XV actually wore potato boutonniere to get people to think they were kind of safe. Two Polish scientists in 1928 published a paper in which they had two young people. They never said they were the young people, but I kind of suspected perhaps they were one man, one woman. And for six months they fed them nothing but potatoes. A little bit of fat to cook the potatoes in and a little bit of fruit to avoid deficiencies. So the only source of protein for practical purposes was the potato. And what they showed was nitrogen balance was perfectly fine. And despite sort of this quote, unquote, bad carbohydrate, or at least some people think it's a bad carbohydrate. No one got diabetes. They didn't gain weight.

C (14:21)

Sure. Just a couple of factual points of clarification. So, yes, I have a grant from and have been a paid advisor to the David Protein Company. Second, the David and David Protein is not my David. I don't own the company. I like the bars. I eat them. And every time I take one out at a meeting or something, someone will look at me and say, how vain are you? You have your own personalized bars with David printed a big. I said, no, it's not me, it's Michelangelo's David. The idea is, you eat the bar, you'll look like that, David. But I've also. We had a protein conference we ran about six months ago. It was amazingly successful. The degree of interest from academia and industry and others are tremendous. We must have had somewhere on the order of 50 different companies contribute. So I'll disclose that as well. So I have a lot of interest in this. I've had funding from National Cattlemen's Beef association, pork producers and other groups with interests in protein. In terms of the idea of does that make us trustworthy or not? I distinguish that from trusted. Whether or what makes us trusted, that's somebody else's judgment. Trust me or don't trust me however much you want, that's up to you. Trustworthy, I think, has to do with the processes. And my colleagues and I, we have a saying we've sort of coined and we like to use a lot. And we say in science, three things matter. The data, the methods used to collect the data, which give them their probative value, which shows what they mean, and the logic connecting the data to conclusions. And everything else is tangential. And so some people who don't have the goods on an argument will resort to other things. They'll resort to ad hominem attacks, they'll resort to innuendo, they'll resort to quips. Quips are great. Innuendo and ad hominem attacks, not so great, in my view. But none of those are dispositive. And when we think about things, we can really declare things known or not known. No one needs to argue about your conflicts of interest. If you say that I can prove that there's a greatest prime number, and people say, well, no, Euclid proved there isn't. And I don't have to say, maybe you're paid for by the prime number company or something, I can just say, here's the proof and you're wrong, and there's no point in discussing anything else. The prime number company.

C (18:31)

I think the answer is things will get better whether it's a step function or not. I'm not so sure I want to expand or add to the branch you've thrown in and add a parallel branch, which is. I think there are two reasons why nutrition science is so fraught. One you've pointed out is the methodologic challenge. Can we collect the kind of data we really want with the kind of methods we really want? The other part is the social aspect which you've hinted at until we've gotten to this point, which is why is it so emotional? Why do people attack each other? Why do people go beyond the data? And I think I see that in any area. The more that area of inquiry is related to economics, religion, social values, personal experiences, the more you get the emotion and the deviation from logic and so on. And we see it in whatever people study, child rearing, same sex marriage, anything that has that emotional valence, that everyday experience and so on, leads to more bringing in of non scientific points of view. So I think that's something we have very strongly. And then I think the other we have is the methodologic challenge of collecting the data. I see benefits on both fronts, but I think both will be slow. I don't think in many cases it's going to be a simple thing of if we could just fix that, if we could just figure out how to measure food intake in free living people, well, and we're on the horizon, then everything will be okay. That's important. I hope we do figure out how to measure food intake well in free living people, but that alone will not be a solution, a sufficient solution. What I think on the front of the emotional piece is it's going to come slow. When you look at the arc of history of much of human endeavor, at least from my point of view and the point of view of I think people like Steven Levitt and so on, you look over the long haul, things are always getting better. You smooth the function a little bit, murder rates are way down, violence Rates are way down, education rates are way up, lifespan is up, et cetera, et cetera. Freedom is up. But there are lots of ebb and flow. So we may be in a little bit of an ebb and flow now, but I do hope that things will get better, as they always have some more and more rationality. And that's something that as a scientist, I feel very strongly about. As scientists, we focus too much on immediate trust in science and saying we need to get more trust in science and on immediate issues. How do we get trust in this issue about vaccines or drugs or what have you, instead of saying, how do we get trust in the scientific process? How do we maybe risk losing a battle? Maybe I'm not going to convince people today that what I think about food additives or vaccines or protein or something is quote, unquote, the right answer. And I have to live with that. But if I can convince them that I'm an honest broker and here's how science works and we can work together through science in the long run, I think that's better and I think that's coming and something we need to focus on. In terms of the nutrition per se, we have so many challenges, but as a methodologist, I like challenges. Job security and it's fun. I like figuring things out. So we can't randomize to everything. So how do we get causal inference? We can't blind every aspect of diet. And if we could, we'd be missing some of what we're trying to study because some of the effects of diet involvement, the effects of perceiving what you're eating, some of the effects of this drink I'm drinking is how it tastes. And if you blind me to it, then you've taken away that potential effect. There are issues of measurement. How do you know what I really ate? There are issues of adherence. If you tell me to drink one of these every day, do I actually do it? Do I drink one and only one as you've instructed? There are issues of duration. Could you get me to drink it now and measure Something in me 15 minutes later? Sure. Could you get me to drink one every day for the next 20 years and measure stuff? Difficult. There are issues of the model organism. One thing is we're going to talk about longevity a little bit. Somebody once said to me, you never want to study longevity in an organism that lives as long as you do. It's a bit of a challenge. If you and I at our age were to start, especially mine, I'm a little older than you were to start a big study and say, I want to study 20 year olds and give them different nutrition and see who lives longer and that'll help me figure out for myself what to eat. I'll be dead long before the study is in and not be able to benefit from it and also not be able to find the answer. And maybe we want answers before 60 years from now. So those are just a few and I could go on and on. Those are just a few of the many challenges we have in nutrition and I think we're going to chip away at them. But a lot of it's going to have to be settling for various rough inferences to say this information, I need to recognize its limits. I need to be honest with the public about the limits. I need to say, I haven't shown this unequivocally, but it looks like this is the most reasonable answer now or the most supported answer now. And I'm willing to accept that. But let's be honest, it's not demonstrated. Great example of that. You're seeing the feud in the literature now between Kevin hall and, and David Ludwig on the use of crossover designs as an example and crossover designs in which you give person, let's say diet A followed by diet B and you give other people a randomized to diet B followed by diet A. They have an Achilles heel that is not there for, let's say, parallel groups where it's just some get diet A and some get diet B. And that is you can have what's called carryover effects. And it turns out I've started to study this. Tip my hat to David Ludwig who pointed the issues out to me and I hadn't fully comprehended them before, that there's almost no way around it.

C (25:50)

You're absolutely correct. And when you said statistics in the or power, rather in the beta sense, that is what it is. It is statistical power. The probability of rejecting the null hypothesis if the null hypothesis is false, which is 1 minus beta, the type 2 error rate, there's actually a little bit more. But I think 90 plus percent of the motivation is what you've described the other as. Actually, Kevin pointed out to me in some dialogue we were having was sometimes it's just throughput. Even if I had infinite money, I can't put people through the procedure fast enough because there's only so many chambers. Someone else pointed out to me it could be patient availability. If you said, I'm studying this in this rare population, I can't get 1,000 people even if I had the money, because they don't exist, I can only get 10 or 20 people. So all of those things strongly favor the crossover, which in almost all circumstances will be much more statistically powerful, meaning you can get the same amount of precision out of many fewer subjects. But the problem is that you have this carryover, and so that the difference between the two groups who get treatment A and treatment B in the second period could be a function of the true effect of treatment A versus Treatment B in the second period, or could be an effect of what treatment A and treatment B did in the first period, carrying over. And now you don't have a clean estimate of the effect of treatment A or treatment B anymore. Now what you can do is what you said is a washout. If you said, I understand how this thing works and it's a molecular effect, it's not a social effect, it's not learning, it's not a surgical thing, and then cut a piece of their anatomy out that doesn't reverse this thing is completely reversible, it's completely Blinded, I gave a long enough washout. Then by that argument, you can say, I rule it out. But you can never say I absolutely rule it out if you're dealing with things other than that, where you can't have a long enough washout. Or it might be a psychosocial effect or a learning effect or some permanent effect, anything from bariatric surgery to something like an allergen which may permanently sensitize the body. I know people say MRNA vaccines, maybe the MRNA hangs around for a while. Is that a permanent effect? Or a vaccine itself is a, we hope in some cases is a permanent effect, like a measles vaccine. All of those things, they're not gonna wash out. So those are things where the crossover has a limit. And the question is, does that mean you try to do what David Ludwig is, I think, arguing again, I hope I'm not inappropriately putting words in his mouth, is saying they're just invalid. Just either don't use them at all or you can only use them in this way. And if you get what looks like it might be a period by treatment interaction, then discard the study, it's invalid, so on. Or do you say, which I think Kevin would say and I would side with, is accept the limitations of the study. It doesn't mean it's a flawed or incorrect study. It means it's a limited study. And as long as you point those limitations out, you may or may not want to accept it. In the same sense, if you have an observational epidemiologic study. I think most of us, again, there are exceptions, but most of us would not say, never do one again, they have zero value. What we'd say is they're not invalid studies in and of themselves. What they do is they leave open alternative explanations for findings other than causation. Could be some bias of measurement error, it could be some bias of sampling, it could be some reporting bias, it could be some confounding, et cetera, et cetera. And we say as long as you acknowledge those, then the study shows what it shows. It's weak inference, but it's not nothing. And I think the same thing is with crossover. And we may have to accept that with lots of stuff, that's the idea of nutrition. We may have to accept there are these limitations of our knowledge. So, for example, if you do a study of cheddar cheese made in Wisconsin versus some appropriate control and you say, look, this is what the effects I get of this. And so therefore cheese consumption has this effect, I said, well, Peter, Are you sure it's cheese consumption in general, or is it just cheddar cheese? Is it just cheddar cheese made in Wisconsin or is it any cheddar cheese? Is it only cheddar cheese when eaten with these other things or these? And I think that's something that's so hard to control in nutrition that we'll wind up with these statements of saying, it looks like it's cheddar cheese in general, and maybe we can do some other studies to suss it out, or it looks like it's cheese in general, but we'll always have this sort of saying, this looks like what it is. Here's a good recommendation. But it's not absolute knowledge.

C (32:50)

In the case of protein, if we're thinking about it not in an absolute sense, but as a percent of calories, let's just say, and let's assuming your calories are at an appropriate level for whatever it is you want to your life. What I think we can say with pretty good confidence is there's some level that's too low. I think we can also say with pretty good confidence that there's some level above the RDA that with very, very rare exceptions perhaps is at most not worse than, and in the vast majority of cases likely better than the RDA level. You might think of it as the real base level, like economy rental. And then there's the higher end good rental. And then there's something further out there where I would say there's less certainty. And that's where probably a little more of the debate is. So there's not no debate between the base level and what I'm saying is closer to the perhaps I don't want to use the word optimal because that implies a dip, but superior, known superior level, little debate in between, but not so much in my view. And then there's more debate about beyond the known superior level and a lot of uncertainty there. I think the evidence is very clear that when you go from the RDA level of 0.4 ish grams per pound or 0.8 ish grams per kilogram up into roughly double or even a little bit more of that, roughly 2. I know no evidence of harm in any group other than perhaps again the very rarest folks. And even that would typically not be protein in general. It would be specific types. So if you said to me phenylketonuric can't have phenylalanine, okay, fine, someone who's got allergy to whey protein can't have whey protein. But that does mean protein in general. I know of no evidence for harm even in people with chronic kidney disease or anything else. I think there's lots and lots of evidence for benefit in at least medium term observable Phenomena like body weight, like appetite control, like bone strength, muscle and so on for people to be consuming more. And I think it's especially true in people who are recovering from injury, bodybuilding, looking for performance in athletics, looking for strength, who are older, who are growing, all of those things.

C (53:48)

CVD type outcomes. So biomarkers, obviously, with the exception, I think, of triglycerides. My recollection is the traditional trans fat sat fat were worse. I think the low fat, high carb was worse for triglycerides and the high fat corn oil type stuff was better for everything that's published in ajcn. Marie Pierre Saintonge was the first author of that. And it was interesting, the criticisms we got. Again, it was. Marion Nestle was one of the few critics and it was typical. Never touched the science. They never said, well, the design was wrong or the measurements were wrong. It was like, well, they were funded by industry. And I call this. This was her words. I call this a calorie distractor. If you have something to say about the science, why don't you Stick to the science and do that instead of quips and ad hominem attacks. But that's all we got anyhow. So the food industry traditionally has not done a lot of this. These studies are expensive. That study we did, I don't remember the exact number, but it's probably in the neighborhood, especially if we inflated it to today's cost. Might be getting close to a million dollars or something. But that's nothing compared to what we talked about with pharma. The other issue is the other big funder is nih. And nih, I think both, has seen often these things as something the industry should fund. Well, I mean, if it's their selling it, let them fund it. That's one. Sometimes it's not seen as really deep big science. Yes, it's practically interesting, Dr. Allison, but where's the big deep scientific hypothesis? And then the last thing is, in my opinion, here's clearly an opinion, the misprioritization of funding. And this is something that now we see the NIH addressing very vigorously. Again, I would agree with some of what they're doing. I disagree with some of what they're doing. But Jay Bhattacharya, he's a real smart guy and he with others are trying to say, let's repurpose some of the funding. Less here, more here. And I look at the observational epidemiology, which can be very expensive in nutrition. And I think the new information yield, and I underline that phrase, new information is often very low. If somebody else comes out with a new study tomorrow and says we did another one and it was a million subjects and we measured the food intake as carefully as we can with self report in this population. We had a couple of biomarkers and there's something interesting about this. And here's what we showed with protein intake and longevity. I don't care which direction it's in. You showed greater longevity, you showed lesser longevity. I already knew it was a question. You haven't answered the question for me. You gave me a little thing to scratch my head about, maybe, but it didn't really move the needle.

C (56:55)

I think the most important thing that I want to say is a sort of a, maybe a little bit of a weird kind of left turn on this. But I think the greatest limit or problem with the nutrition epidemiology in a context like we're discussing now, or in this exact context of protein consumption and things like longevity and long term major health is the opportunity cost. It's that we're spending the money, and often a non trivial amount of money, these big epidemiology studies can be very expensive and we're not spending it. Therefore, in the big randomized, well done, controlled clinical trials, that's, I think, the biggest problem. If you said to me, well, we did some epidemiology, there's something we can glean and it's interesting and fun and there was no cost. Okay, what if you say we did that, but we could have done one really good, or maybe 10 medium sized randomized controlled trials for that? That was a big loss. Now, in and of themselves, if we just stick to the epidemiology, you and many others frequently and correctly point out the issue of confounding. We all say correlation is not necessarily causation. The example of ice cream consumption and murder rates is trotted out. We say, you know, more ice cream consumption associated with more murder rates. Guess what? It's heat. People eat more ice cream, it's hot, they murder more when it's hot. All true, all fine. But that's actually just a tiny piece of it. There's so much more. There's the measurement problem. And that measurement is not random. And even if it was random, it's usually not taken into account. If it was random and we knew it was random and we took it into account statistically, we could make the problem kind of go away. But it's often not random. It may be correlated. People who eat more of this may systematically bias their reporting down than people who eat less of that. There's selection bias. People may choose to be in the study or not choose to be in the study and that may affect things. There's what's called collider bias. I control for something and I think I'm doing a good thing by that. But in fact, I've created an inadvertent association. I could go on and on with statistical obscura.

C (66:59)

I think the implication was the saturated fat or maybe the saturated fat and sodium. So in any case, I think we need to do better with that. I know of no compelling evidence for harm. That doesn't mean there couldn't be any. But I know of no compelling evidence for harm. I know of no studies showing that humans get more cancer with this. I think we need to be skeptical of the mouse studies, the epidemiologic studies, for reasons I've indicated. I think at some point we need to recognize, as people did. When I put up that LinkedIn post and I said, show me the data, can anybody send me one? Many people responded with something akin to, I can't show you that study, David, but can you show me the complement or the opposite study that meets all your criteria and shows there isn't harm? And the answer may be no, I'm not sure. But what I can say is at some point when you've looked enough and you've failed to see harm, where is the burden of proof? So if you don't have a really strong a priori rationale, now we can argue about that. There probably is legitimate debate. You might legitimately say, I have a strong aprior rationale, there isn't harm. And Dudley Laming might say, I have a strong a priori rationale, there is harm and you're entitled to your opinion. Those are opinions. And then we can both look and say, well, neither one of you has the absolute definitive data. At what point? Where's the burden of proof? And I think right now the notion is the burden of proof is on those who want to argue for higher protein intake. Well, the evidence isn't clear enough to show that the RDA is too low. To which I would reply, well, the evidence isn't clear that it is isn't. Now, where does the needle point? Where does prudence point? And I don't think the status quo is necessarily what's always prudent. Saying, leave everything the way it is is always the best way. Sometimes it is. But in this case, I think we've left it alone long enough. I think it's time to say we've looked and looked and looked. If I look at a thousand swans and I cannot find a black swan, does that mean that no black swans exist? Of course not. But if I looked at 10,000 black swans, if I sent a helicopter in the air and we scoured and we looked with binoculars, if I sent teams of undergraduate students to walk around ponds and measure look for every black swan, if I put drones with cameras out and I have failed time after time after time to find a black swan, at one point, say, maybe for practical purposes, I can say black swan's probably not something we need to worry about.

A (69:34)

Yeah, I think that is probably the most logical way to frame this, which is, I do not believe we're ever going to get a dose toxicity study for protein the way we do for figuring out what the LD50 of a drug is, where you push the toxicity and you figure out, okay, at this dose, we will kill 50% of people. So the real question becomes, what would be the bracket you would put around for 90% of the population to exist within this range is an appropriate way to interact at the grocery store? To your point, what's the problem we're trying to solve here? The people listening to us don't care about most of what we've said today. I mean, we had to say it, but they actually just want to know. Look, man, I'm really confused because I'm reading people who have a lot of piss and vinegar in what they're saying on this topic. How much protein should I be eating? What should my family be eating? Should I be avoiding protein in my kids? Should they not be eating snacks with protein? Whatever the argument is. So our guidance to our patients is pretty straightforward, and it varies based on their preference. We have some patients who are vegetarians, who have been lifelong vegetarians, who can't stand the feel of meat. This is not like a belief that they have that meat is bad for them. They genuinely don't like meat. We have other patients who won't eat any animal products. So they're going to have a harder time reaching the upper limits of protein consumption. And so with those people, we're just trying to nudge them as high as we can get them. And that's probably not going to get much higher than about 1.2 grams per kilogram of body weight. But the guidance we're giving people is we really like to see you at about 1.6 to 2. It's an easy heuristic. It's easy to remember, too, because you're basically consuming almost a gram per pound of body weight. So how would you advise people based on the. Tell me the. For all intents and purposes, you don't need to worry about Black Swan's argument.

C (72:45)

Great analogy. My uncle, my great uncle, who was a professor from the old country and the old school and a philosophy professor, when his kids would come home in America from school, he would say, good, now playtime's over. Now you sit down and we study Latin and math and logic, and you do the real work. And then there's probably yet another example. You may know that in South Korea, they actually had to pass some laws recently, or chose to pass some laws recently that I forget the details of them, but that students could only study so much because they're really starting to get worried of students just going too far. And I think those are good examples. To me, it's sort of like the RDA for protein intake is like what my uncle saw the American schools as. It's like, yeah, this is just enough to pass high school and do something. The next level up is what my uncle did, which was we're going to really do some work and get you closer to an optimal level. Maybe what some students do is maybe go too far. But I also think it's interesting to see in what way were they going too far? Did anybody ever say or show that if you study algebra or anything else 12 hours a day instead of 2 hours a day, it directly causes harm? And I don't know of anything like that. Now, if you said to me, if you study algebra or whatever for 12 hours a day, ipso facto, you are not exercising, you are not socializing, you may be not sleeping enough, et cetera, then you have a problem. It's not the direct effect of the studying, it's the substitution effect. Right? So if I literally drank, I handed you a drink when we came in. One of my favorite playtime things. I love to play with these different protein products and have fun with them. And this is a drink that has 20 grams of protein and 90 calories, almost pure protein. And there are other things like that. If you or I were to say, I just want as much protein as I can, so I'm just going to live on that stuff, there would be no, to my knowledge, no direct harm. I'm not worried about my kidneys shutting down or something. But I would say, well, wait a minute. Did you have any vitamins and minerals? Did you have any pleasure from eating other foods? Did you have enough energy to work out hard by not having any carbohydrate? Maybe a little carbohydrate would make you work, able to work a little harder. So I think there are other losses, but beyond those other losses, or if you get a fatty acid deficiency because you have an nadalinolic acid, beyond the losses, I don't know of any risk. So to me, I look at it and say, life support, basic maintenance, RDA, strong evidence for thriving. 2ish above 2, probably more benefit. But you're starting to hit the asymptote. I don't know that it's going to come down. I don't know of anything that says that it's not going to be monotonic. That's going to turn around. But diminishing benefit and then starting to get into more costs of economic costs, of buying fancy products, of the cost of your time and attention on it, the costs of not eating something else you might like. I know you and I have both, I don't know, struggled with is the right word, but wrangled with fruit. We both like fruit and we've both played with diets at times where we've minimized the consumption of fruit for other goals. And yet both perhaps come back to it a little bit and said, I don't want to give up Fruit. And those are examples, I think, where there's some optimization, but I see no harm. And I think the more refined your goals are, then the more it's reasonable to push it a little bit. If I wanted to win the Olympics, I'm more motivated to push it. For me, if I can lift one more pound of weight on the bench press, who cares? But if I'm trying to win the Olympics, then it matters.

C (82:45)

Wow, you've given me so much to work with. One thread I just want to throw out quickly. We may or may not have time and interest in coming back to it is the idea that fewer calories are better, at least to a point. To a point is true. But one of the things, particularly with protein, is we look at some of these studies that people are citing. So I realize I'm sort of looping back to our prior conversation, but these are from the mouse looking at longevity. And it's interesting they're very dependent on ambient temperature. So the studies of caloric restriction in general and protein restriction in particular, which show benefit, are much more present at 22 degrees Celsius, which for a mouse is a thermogenic challenge, thermoregulatory challenge, as opposed to thermoneutral conditions, roughly 27 to 30 degrees Celsius. We don't live our own lives in chronic cold, so we'll leave that out there and say it depends on the conditions. There's several threads you've allowed me to pick up here. One has to do with the idea of categories. All categories are social constructs. We often hear that said about things like race. It's true. Race is a social construct, so is furniture, so is vaccine, so is medicine, etc. What you choose to use as a category and how you choose to define membership in that category is a judgment call. And it's not intrinsically written in stone what that should be. They're useful or not useful for your purposes. That's the first thing to point out. So, same thing as ultra processed. There's not a correct definition of ultra processed. You can define it any way you want. The words mean what we say they mean. Once you've defined it clearly, then we can say, what's its value? How can we use it? What's its utility? Second thing I would say is, as with any category, if it permits a lot of variability in that category, which ultraprocess certainly does, it starts to get a little silly to talk about the overall category because you say so. Wait a minute. You want me to consider a meal replacement shake in the same category as I consider a Big gulp in a 711 in the same category, I consider a chocolate bar in the same category. I consider TPN nutrition. These are all arguably ultra processed and very different things. And I think we want to talk about the things. The next thing I want to bring up is what are we trying to do with it? And this is probably intellectually most important. If you say to me, David, what I am looking for is a heuristic. And this loops back to something I said we'd address later or earlier I mentioned. I said we'd come back to it. The distinction between how much protein do I think somebody ought to eat for a certain goal versus how would I tell them to eat it or what would I tell them about? And those are two different things. If you said, david, I just want something I can tell people so that when I tell them this, it has a beneficial effect. Does telling them not to eat ultra processed foods or to eat as few of them as possible. Defining ultra processed in this way help? The answer is might help a lot. It might vary a little bit depending on how you said it. We need more studies. We need to figure out. My guess is, as with everything else, it won't last long. So you could tell them not to drink sugar sweetened beverages. You could tell them not to eat fettuccine Alfredo because it's a heart attack on a plate. All these things have a small effect for a while and usually not so much for a long term, but it might help. We need to study that. That says nothing, however, about the effects of the food per se. If you said no, David, my goal is to tell people about the foods they should eat, if they actually ate them, what the effects would be. My goal is to determine the effects of foods. Then I would go back to a statement from a wonderful book called A Fly in the Ointment by someone named Joe Schwartz. And Dr. Schwartz, who's a food scientist, says something like, there is a motto. Repeat after me. The effect of substances in the body depends on their molecular structure, not their ancestry. So if you give me this molecule or a collection of them to eat and you extracted that molecule from some berry and it's natural, or you synthesize that molecule in a laboratory, but in the end it's the same molecule. We agree. I mean, you could try to synthesize it, might have some slight difference, but let's assume it's literally the same molecule and it's the same structure. You give it to me in liquid form. In liquid form or in gaseous form, whatever it is. If you say these are going to have different effects because of where they came from. Seems to me we're in homeopathy now. This makes no sense.

C (90:27)

13 of them, if that's the logic of your thinking. I have a great product I'd like to sell you. It's gluten free, it's seed oil free, it's not ultra processed, it's free of any harmful thing, it's chemical free, has no chemicals in it. I call it vacuum. And I would like to sell you this vacuum. And basically that means nothing because we are chemicals. As my friend Ferg Clydesdale, who's the former head of the nutrition food science department at UMass Amherst, used to say, the whole purpose of eating is to get chemicals into the body to replace the chemicals the body loses through the process of living. All food is chemicals. We are chemicals. When you eat that apple and you say, I understand it, that's apple, unless you have a lot of chemical knowledge I don't have, and most people don't have, you don't understand that any better than you understand something else that says benzoate phosphate or what have you in it. You just think you do because you think you understand what an apple is at a chemical level. You understand what it is at a fruit level, maybe, but not at a chemical level. There are many chemicals in an apple and an orange that you or I couldn't pronounce. And that if someone wrote out what the chemicals are, we would say, what is that scary sounding thing? And we also know that things that we think of as natural can be just as harmful. Foxglove, hemlock, Socrates killed by being forced to drink all natural hemlock. It was all natural, very harmful. So poisons, drugs often come from natural things. There's also a misperception that what we think of as natural is somehow has been around for thousands of years, and in some cases it's true. In many cases it's not. So the oranges and the apples and the grains that you're eating today were largely not around years ago. They've been bred, even if it's not transgenic. They've been bred by ordinary breeding things. The cows, the chickens, the pigs have been bred to be different. They are not indigenous species. All the chicken, all the cow, all the pig that we eat in this country, the soybeans, none of that's indigenous. They're all invasive species. Turkey that's indigenous to North America, pecans and black walnuts, but not the other walnuts that they love so much in the Mediterranean diet over there. They're not American. I think this is all silliness. The only thing that's artificial here is our creation of these categories. And we should just recognize that we create the categories. Let's make them meaningful and useful. So back to ultra processed foods. If you said to me, I'm just looking to give my patients or my friends or my mom or myself a hint, a heuristic, there are lots of heuristics that don't, don't require that classification, right? But There are also lots of heuristics that work, even though there may be some illogic embedded in them or some incompleteness or some variability. If you said to me, for example, don't talk to people on the street who look like this, if I was your kid and you said, look, you're walking down the street, you're in a big city, someone comes up, asks you have a match, just keep walking. It's probably a good heuristic. They probably don't really want a match, but some might. And you might miss some, but it's not a bad way to stay safe. Similarly, if I said to you, you know what, don't eat anything from the center aisles at the grocery store, or as little as you can, get as much as you can from the periphery, the dairy, the produce, the meats, the fish and so on, you might be better off. You will wind up eating less ultra processed foods, you'll wind up eating less energy dense foods in many cases, et cetera, et cetera. But that doesn't mean there's something intrinsic about the periphery of the aisles. Doesn't mean if I took Twinkies and put them in the periphery and I took fat free Greek yogurt and I put it in the middle, that suddenly it becomes bad and Twinkies become good. It's a heuristic and it might work for you. To the extent you can stick to it and to the extent it's correlated with these things, it might work. But it says nothing about the causal effect of being in the periphery or the central aisle. And I think as long as we take ultra processed foods at that level, hey, power to you. In the same sense as if we were talking to that person back with the protein said, how do you explain it to them? Maybe you don't say eat 2 grams per kilogram because that's too hard. You have to use the metric system and Americans hate the metric system. And you have to do math and so on and you have to count stuff. But if you just said, make sure you have two servings of lean fish per week and one serving of lean this and eat some egg whites and so on, maybe that works. And we all have our own foods. During World War II, they tried to get Margaret Mead. They hired Margaret Mead, the federal government, to try to get people to eat more organ meats because they wanted to send the steak and all to the soldiers overseas. Didn't work. Even Margaret Mead couldn't get people to eat a lot more organ meats. I happen to love organ Meats and some of my go to protein sources are chicken gizzards. Fantastic protein to calorie ratio and I love them. A lot of people look at that and go, no, we need to figure out the way to get people to do this. But it's the food that matters, not this. Now if we go back to those idea of wanting to understand the food, the effects of the food, then I think working with ultra processed food is just silly. I think it's not a meaningful category. I think any attempts to say let's find the right definition, I wouldn't even bother. I don't even think it's worth even discussing. I would say is let's talk about the substances in the food. What is the effect of eating dried apples or what is the effect of eating things with this composition? Or what is the effect of eating bottled wine or dried dates or grilled chicken gizzards? That's I think, where the knowledge is.

C (99:50)

It can't be for lack of trying at all. It may be for lack of trying in a little more intelligent and unbiased manner. I think there's two really big reasons. One is intrinsic to the problem. One can never start smoking. For some people, as difficult it is, one can abandon it entirely. One can't never start eating and one can't, for practical purposes, abandon it entirely. So it's a different problem. You've got a very strong intrinsic push there. I mean, it's so linked to our survival. It's a hard goal to manipulate. I think it's intrinsically just very, very difficult. We like our freedom, we like our variety. I don't want to give up my freedom and variety. If somebody were to say, if we eliminated all of these choices or you're only allowed to shop on Monday or you're only allowed to buy X calories, it's like rationing in a war because some people are obese. Even though I myself have struggled with my weight, I would say I don't want to live in that world. I don't want to give up my freedom of choice, even if it means I and some other people are going to struggle with our weight. So I think there's some real intrinsic difficulties. Everything we do in the public health realm almost seems like either we can't get it to stick or we didn't think through enough. If it stuck, it would work, or it's like whack a mole. That is, you get me to consume fewer calories here or expend more energy there and then I expend less here or consume more there. So I think that's the intrinsic problem. And then I think the other problem is that we started off with the obvious stuff. We looked for the keys under the lamppost because that's where the light was best. We said, ah, school based approaches, farmer's markets, walking trails, calories on the menu. So on good ideas, all good ideas, nudge. We tried them. None of them really seemed to work meaningfully. At the beginning that was fine. What I think we have is a failure of courage, honesty and creativity to say we've shown that none of those things have large, demonstrable, meaningful effects. We've not shown that none of them could ever have any effect under any circumstance. But I think for practical purposes we've shown that those things don't have large demonstrable, meaningful effects. And I think it's time to stop pretending that they might and proposing and funding the next study that's only a trivial variant on the many, many such studies that went before and were shown to not be successful. I think we need to start taking radically different views and say the next time someone comes and says I've got this parent based or school based or community based idea, tell us how it's radically different than what's gone before. Not trivially different.

C (105:43)

Obviously not the same exposures may not have the same effects in one place or another. For example, we consistently see that in less developed countries, poorer countries, less industrialized countries, greater wealth is associated with greater obesity. We consistently see in more industrialized, wealthy countries, greater wealth and education, especially among adult women, tends to be associated with lesser obesity. So you have the interaction. The other is, as you and I had said earlier, the strength of the evidence. One of the things people frequently like to say is when you say, well, we think temperature has this effect and they say, what about those people in Iceland? They don't have. Well, alcohol is this. Yes, but those people over there, they drink a lot and they don't have. They're different. They're different in many ways. We don't know that. You know, any one factor has to explain why Qatar has this versus Samoa or something. But I think it's a good hypothesis. So that's what I would look at at the public health level in what we think of as traditional public health. Now with the GLP1 agonist related drugs and some other drugs being as profoundly beneficial as they appear to be, I think we're going to get to the point where it's going to be hard. I think we're already asking the question and I think it's going to be hard not to take the question seriously of should it almost be the default that is just like we've asked the question and people give different answers, but we ask the question, should it be that the default is you get this vaccine when you're a kid, that you get your teeth fluoridated at the dentist, that it's not. Maybe some people should get that. I think we are at the point where we're saying as these drugs continue to be tested and experienced, if we continue to see the effects we're getting, are we getting to the point where we should start to say, you know what, that idea of the poly pill that came up decades ago where young adults, even if you don't have diabetes, obesity, hypertension, et cetera, you'd get a low dose diuretic, low dose metformin, et cetera, low dose statin, orthopormists probably still should do that, and then say, anybody get a low dose GLP1 agonist related drug and we'll roll it out and we'll pay for it, and anybody in the country who wants it can get it, or almost anybody. I think that may be the future.