Dr. Herman Pontzer: How We Really Burn Calories & Lose Weight

**Andy Galpin** (0:00)
The science and practice of enhancing human performance for sport, play and life. Welcome to Perform. I'm Dr. Andy Galpin. I'm a professor and scientist and the executive director of the Human Performance Center at Parker University. Today's guest is Dr. Herman Pontzer. Herman has a PhD in Biological Anthropology, and is currently a professor at Duke University in the area of evolutionary anthropology. In today's show, you're going to learn a lot about what Herman is probably most famous for, and that is how metabolism really works. We talk at length and you'll learn a tremendous amount about how to properly think of energy expenditure, the role that exercise does, or maybe surprisingly doesn't have in things like energy expenditure, body weight, body composition, and overall health. He also does a wonderful job teaching about how energy expenditure changes with things like pregnancy, and other things we don't typically think of as exercise or sport, but are highly relevant and incredibly interesting regarding how our metabolism and overall physiology works. So there's a lot of practical tips here. There's a lot of just fascinating information. I know you'll enjoy it. I was thrilled to do it. I waited a long time to talk to Herman. So with that said, please enjoy today's episode with Dr. Herman Pontzer. Dr. Herman Pontzer, thank you for coming in today.

**Herman Pontzer** (1:20)
It's fun to be here.

**Andy Galpin** (1:21)
It is a huge honor. I've been wanting to talk to you for a really long time, even before I had a podcast.
Your work is incredibly interesting. I'd actually like to start with exactly your work, in the sense that your PhD is in anthropology from Harvard. But you probably are most, I'd say, notable for setting the world on fire a little bit with some interesting and controversial takes on metabolism, how the body burns fat, the role of physical exercise. You had a series of papers come out that, I'd say, put you on the map. If that's a fair way to put it. So what is it exactly that you do? Why is a anthropologist changing the way we think about metabolism?

**Herman Pontzer** (2:03)
That's a great question. So as an anthropologist, I'm interested in how the human body works and how it got this way. It's sort of an evolutionary lens on the way the body functions. So coming up through my training in undergrad and then graduate school, I never had any sort of public health or obesity research interests necessarily. I wanted to understand energy expenditure, though, because it's where the rubber hits the road, you know? Any organism is, you can think of it as a strategy for turning energy into offspring, right? That's the game in life. And so from undergraduate up to graduate school, I was very interested in how the body brings energy in and burns it off. And you start following your nose that way, and you get into some interesting places, because trying to understand how locomotion burns calories and how that relates to anatomy, that was my graduate work. OK. And then when I kind of thought I understood that pretty well, I built like a put together a mathematical model for predicting the energy expenditure to go walk or run a mile, depending on how your limb anatomy looks. Right. I felt like I understood that pretty well, and I thought, OK, let's expand that. Let's think about a whole energy budget. How does a whole chimp or a human or anything, how do we bring energy in and burn it off over 24 hours? The whole shooting match.
It turns out people hadn't really been doing a lot of measurements of total energy expenditure, all energy burns for the whole day. In humans, outside of Western context, we had data from the US or Europe. We didn't have data from traditional context, which is more relevant for human evolutionary perspectives. We had no data on the other apes, that kind of thing. So I started this whole last 20 years has been trying to measure energy expenditures in these contexts from an ecological evolutionary perspective. And then we wind up in some pretty interesting territory.

**Andy Galpin** (3:58)
Your first book, Burn, walks through a lot of these things. But just as a starting place in the story here, what is this deal with this hunter gatherer group? What did we get wrong with the paleo diet? Give us the real quick overview there.

**Herman Pontzer** (4:13)
So again, from an evolutionary perspective, how do we understand our body? Well, we are hunter gatherers, right? Humans have been hunting and gathering since before we were humans, right? Two million years. And our species is only 300,000 years old. So that's, we are a hunting and gathering species. That's the ecological context. And so if you want to understand how the body works, California is fine and New York's fine, but more relevant would be a hunting and gathering context. And so luckily, there's still a handful of communities that are still doing that. And they're not like time machines of the past or anything like that, but they give us a sense of, okay, if you have this lifestyle in this ecological context, this is how the body would function. They allow you to ask that question. And so nobody had measured energy expenditures in a hunter-gatherer group before. I had some colleagues that were working in northern Tanzania with a community called the Hadza. And so we went there and did this work. And so we use this technique called double-labeled water, which is this isotope-tracking technique that's a really accurate measurement of how many... It actually measures how much carbon dioxide the body makes every day. So that tells you how many calories. It's over about a week or two week period. So it's a really good look at how many calories you're burning. And we wrote those initial grants to go do this project because we wanted to document just the huge amount of calories that we were sure they were burning, because they get more activity in a day than most Americans get in a week. Right. And so we're like, well, that's the way that humans used to live everywhere. Let's understand what that does to the body. It's the calorie expenditures are going to be huge. Nobody's measured it. It was exciting to go do this work, right? And so we go there to Northern Tanzania, 2009 and 2010, armed with isotopically enriched water and the whole kit. And we do these measurements and we get back and get the data set back.