Constraining Anorexia

Published 3.10.2026: Over the weekend I listened to a few podcast interviews with Duke University professor Herman Pontzer. Here is one of them. I have talked about Pontzer and his work before, I have read and reviewed his first book. I have not read his second yet.

My bias upfront: I am not convinced about the contrained energy model. I get that metabolic adaptations exist, and you can’t keep losing forever if you increase exercise. I also understand that weight loss is driven by nutrition, at least principally. It is, after all, Calories In (food) vs Calories out (everything else Including exercise— some of which you can control, some of which you can't.) However, I think if a person is not an elite athlete, the additivie model works pretty well. Essentially, I think that any so-called “constraint” only occurs in extreme instances.

Which brings me to the topic of anorexia, which I’m not sure if the energy constrained model can explain. Of course, the proponents would say that it’s a moot question, because anorexics starve themselves… but I’m not sure. The few (mercifully) anorexics that I’ve known have also used exercise as a way to limit calories. And they don’t seem to be constrained in terms of weight loss. But the issue is complicated by their nutrition (or lack thereof).

So by the constrained energy model, you couldn’t become anorexic by just exercising. There would be a limit to how much weight you could lose just by exercising. Really just not sure about that.

One of the things Pontzer mentioned was that weight lifting might be less compensated for then aerobic activity… or maybe resistance training has been studied less. Pontzer was careful to say it’s an interesting topic, but that he doesn’t know. I think body builders would have something to say to him, but that’s not data.

One thing that Pontzer said that I didn’t realize is that BMR or basal metabolic rate (basically the number of calories needed to keep the body going) goes down when you lose weight, or exercise. That’s how the body will compensate for increased exercise or enhanced NEAT (non-exercise activity thermogenesis) however NEAT is defined. Pontzer’s NEAT can’t easily be upped or gamed, but whether or not steps count as exercise, I’m going to try and increase them.

Pontzer’s definition of Physical Activity would include getting your steps in. NEAT in his view is thinking, or just not lying around in bed. Or maybe he’s just not using the term? Cuz then he brings up “structured” exercise. Chasing Clarity has a different view (one that matches my own). I’m not sure that it makes a big difference.

At the gym, my BMR has increased (I presume) because I gained lean mass, and muscle burns more calories. But perhaps it’s a wash, because my cortisol and other hormones related to inflammation have decreased. I have no way to measure this, so at best, this is a guess as to what’s happening.

Another topic which came up was the Minnesota starvation and the Biggest Loser study of Kevin Hall. If I wrote about it I never published it, but I do remember the study and the media coverage of it. The question was that Kevin Hall’s result seemed to conflict with the Minnesota Starvation study by Ancel Keys. In this famous study lean, male, conscientious objectors to World War 2 were starved and forced to exercise. They lost a ton of fat mass AND lean mass, as expected.

But when they started refeeding, the regained the fat mass (actually overshot it) AND the lean mass. Their BMRs also recovered, which is in stark contrast to Hall’s results. Now, the subjects in the Biggest Loser were not lean (otherwise they wouldn’t be part of the show). But Hall found that the BMRs of the conestants did not recover.

Pontzer stated that actually, if you looked at the results of individuals, some of the BMRs DID recover. In fact, the more weight the person put on, the closer their BMR got to the original number. So I’m left with the notion that a smaller body (which all of the Biggest Loser participants would have ended with), have smaller BMRs. They simply don’t require as large amount of energy to keep them alive. So maybe there is not a disconnect.

The issue of having to normalize body size came up again. This still bothers me. I get why they do it, the hunter gatherers are much, much leaner than the average Westerner. I’ve written about this before, so I’m not sure it’s worth going over again. Without having a measure of westerner lean mass and the variations found there, I don’t know that choosing an “average” is legitemate. But you can ead at the link if you want more.

The point of this podcast was the talk about the second book, but most of the host’s questions related to the first book. I will make the effort to find the new book and read it. then I’ll write a review.