Professor EXPOSES The Big Myth Around LOSING WEIGHT! | Herman Pontzer

Dr. Herman Pontzer 0:00 Even if you're more physically active, you're getting more exercise every day or you're getting more physical activity every day, that doesn't necessarily mean that you're burning more calories every day than someone who's m- more sedentary than you. [upbeat music]

Dr. Rangan Chatterjee 0:15 I thought we'd start [smacks lip] by getting straight to the heart of one of the bits of research that you've done. And that is that moving more doesn't necessarily mean that we are going to burn off more. I wonder if you could expand upon that, please.

Dr. Herman Pontzer 0:35 Yeah. Yeah, that's right. So, um, even if you're more physically active, you're getting more exercise every day or you're getting more physical activity every day, that doesn't necessarily mean that you're burning more calories every day than someone who's m- more sedentary than you. Uh, and the surprising, that, that kind of goes against, you know, what we're taught and what we're told, you know, uh, both in nutrition classes if you take them, or, you know, whatever sort of basic biology you might have had, or for that matter, you know, every website that talks about, you know, exercise as a way to lose weight or every glossy magazine, you know, just sort of self-help idea about exercise and weight loss. Um, and so it was a real surprise to us, and, and we came to this in a, in a kind of a funny way. We were doing work with really physically active, uh, communities in, in northern, uh, Tanzania, and, uh, measuring energy expenditures. And even though they're more physically active than us, uh, they don't burn any, any different, you know, the, the energy expended per day is no different than you and me.

Dr. Rangan Chatterjee 1:30 Yeah. I mean, that's incredible to hear. I remember, I think it was two or three years ago when I first came across one of your research papers, and for me, it really helped me understand what I see a lot in clinical practice. And I thought, oh, it's so good to see some research there, because you're right, there is this, there's this narrative within the public health community, within the scientific community, but it's gone beyond that. Even within just common everyday conversation with people, it's an assumption that we all have made that m- moving more will lead to burning off more. And that was what's so striking about those early research papers I read of yours, which is it's, it's literally turning that on its heads. So what you're proposing, you know, is, is pretty game-changing for, for, for a lot of people.

Dr. Herman Pontzer 2:22 Yeah, I think so. I mean, w- it was game-changing for us, I can tell you that. It's, it was a total sea change in the way that I think about metabolism and in the way that I think a lot of, uh, us on the sort of basic research side of things. You know, I'm an evolutionary biologist, uh, an anthropologist. I want to understand human evolution and how our deep past, you know, shaped the way our bodies work today. Um, so I don't, I didn't come into this from a clinical kind of public health, uh, training. You know, that, that's not my background. Um, so it's been fun sort of seeing that work, uh, you know, be relevant and be in the discussion in public health. But we just wanted to understand how the body works, right, from a fundamental level, and to discover that, that sort of there's this, this really basic assumption that we're all making that had never really been tested very well. And then to go and test it, this c- uh, this relate, you know, relationship between activity and expenditure, to go out and finally do that work and go, "Wait a second, this is not actually what we all assumed coming in, w- but what we were trained in coming in," um, that was really exciting. So I think it is a game-changer. I think you're right.

Dr. Rangan Chatterjee 3:20 Yeah. I think many people will have heard that and go, "W- what does he mean that, you know, if I move more, I, you know, I know, like, I can, I can-"

Dr. Herman Pontzer 3:28 Yeah

Dr. Rangan Chatterjee 3:28 ... I can eat a Mars bar. I can see the calorie content," and therefore we, you have it in gyms that, "Oh, therefore I can go and, you know, run for 45 minutes now," or whatever the metric may be. So why don't we start at the, you know, right at the very beginning. You know, what is metabolism? How would you explain it to people? What are calories? And theref, and then from there, can you then take that next step and show us why moving more doesn't always lead to burning off more?

Dr. Herman Pontzer 3:59 Yeah. Yeah, that's a great place to start. So, um, so metabolism is just this, the sort of umbrella term for all the work that your cells do all day, right? So you've got 37 trillion cells, and, uh, they all are doing work all day to sort of bring nutrients in, break them down, make other, other, uh, you know, other molecules, get waste out, you know? So this sort of housekeeping work that all of our cells are doing all day. Um, all of that work requires energy, right? And so y- you could measure all the products that your cells make, and some people do that. They study metabolomics, it's called, and they're studying the proteins and enzymes that your cells are making. So you could measure the output, or you could do what a lot of us do, which is measure the energy expended for all that work, and it's, it's basically two different ways of measuring the same process, which is all the work that those 37 trillion cells are doing. Now, um, you know, most of that work we're only dimly aware of, or maybe even not aware of at all. So it's things like your liver digesting your food and, you know, doing all the work that your liver does. Um, your brain. Your brain burns 300 kilocalories a day, right? We're, we're dimly aware of that, if we're aware of that at all. Um, you know, your, your immune system, uh, reproductive system, all these things that, that your s- your body's doing all day, most of it that you're not even, you know, conscious of, that's metabolism. Um, now the parts of it that we're aware of i- are, are the exercise parts, right? When we get moving, we get sweaty, we get our heart rate up. We're aware of that part. And so we tend to sort of equate energy expenditure per day with the activity part that we're, that we can see or we can feel. But in fact, even for somebody who exercises regularly, um, that activity portion of your expenditure is only, it is l- well less than half of how many calories you're spending every day is, is spent on, uh, physical activity. Most of it's spent on all the other stuff that you don't even know. Okay, so, so that's metabolism. And as somebody who's interested in human evolution, and in evolution generally, um, we wanna know how all those calories are spent and where ... Uh, the activity part's cool, but we wanna know about the energy spent on reproduction and on, uh, immune function and maintenance, all the tasks that the body's doing. That's why I get excited about metabolism, because you're sort of doing the forensic accounting-

Dr. Rangan Chatterjee 6:14 Yeah. Yeah

Dr. Herman Pontzer 6:14 ... of, of how the body's prioritizing the energy in and energy out. So- Um, as somebody who's interested in human evolution, uh, you know, y- y- the genus Homo, we're all g- Homo sapiens, right? The genus Homo has been, um, hunting and gathering since, since its inception, since w- you know, it evolved 200 and a half, 2.5 million years ago. And so Homo sapiens, our species, is just the latest sort of twig off this large bough of, you know, the, the, the primate family tree, which is our bough, the, the, you know, genus Homo. And so to understand, uh, what humans are all about, and ecologically and evolutionarily, you need to understand what the body looks like and acts like and works like and metabolizes like, uh, in a hunting and gathering population. That's what you need, right? That's, that's the ecologically real sort of relevant, um, lifestyle for us. But nobody had done it, right? So nobody had, uh, measured energy expenditures, total energy expenditures, in a hunting and gathering population before. And so in 2009 and '10, um, uh, Brian Wood and Ro- and David Raichlen, two of my good friends and, and, uh, collaborators, we went to work with one of the last hunting and gathering populations on the planet, which is this community called the, the, the, their name is the Hadza. So the Hadza community in northern Tanzania, um, they get, they eat all their, foods are all wild foods, you know, plants and, uh, berries and tubers and wild game and honey, and they live in grass houses in northern, you know, in the savannas in northern Tanzania. So they're, they're a, a great, intact, uh, wonderful, hosts, you know, uh, gracious, lovely folks, uh, live in northern Tanzania. And, you know, w- so we went there, and we measured energy expenditures, and the reason we did it, the reason we did all the work to go and, and, and, you know, get the funding and take time [laughs] out of our lives to go and live with these folks for, uh, for a, a long time, it was a long process, um, was to finally understand how many calories they spend every day, how, you know, what humans e- spend every day when you're, when you're hunting and gathering. Okay. So Hadza men and women get about between five and 10 times more physical activity every day than men and women in the US or Europe. So they're incredibly physically active. If you're a step counter, right, uh, the Hadza get about 13,000 to 19,000 steps a day.

Dr. Rangan Chatterjee 8:33 Okay.

Dr. Herman Pontzer 8:34 Right? Plus, they're digging up tubers, and they're chopping into trees to get honey out of the, you know, the, 'cause the bees there put, build their hives in the, in the trees. And, uh, you know, they're carrying babies on their back, and com- I mean, it's, it's a lot of work. So we were sure going into it, we were certain that they would be spending tons more calories every day than we do in the West. That was the whole, that was the premise of the work, right-

Dr. Rangan Chatterjee 8:56 Yeah

Dr. Herman Pontzer 8:57 ... was that we were just gonna go try to document that, that deficit that we seem to have in the West. And instead what we found was that their total energy expenditures, total calories spent per day, is the same, uh, in- indistinguishable from folks in the US and Europe. And so, you know, to get back to this, well, what is, what is metabolism? The answer is, um, it's all those things. It's, it's the activity, it's the immune system, it's... But what, what was happening is, rather than just sort of adding them up in a kind of simple way, obviously our bodies are able to kind of manage, right, and, and make the sort of, um, economic decisions about how to spend those calories so that as someone who lives in a population like the Hadza actually don't have a top-line number of calories per day that's any different than you and me, even though they're obviously spending those calories very, very differently, lots on activity and less on other stuff.

Dr. Rangan Chatterjee 9:49 Yeah. I mean, you call this the constrained energy expenditure model, I think.

Dr. Herman Pontzer 9:54 Yeah, yeah.

Dr. Rangan Chatterjee 9:54 And we have this idea that how we utilize energy is additive, don't we? So if I, um, run for one hour, therefore I have, you know, the, the, whatever the... I, I don't even know how many calories that would, in theory, uh, you, you would burn off by doing that.

Dr. Herman Pontzer 10:16 Yeah.

Dr. Rangan Chatterjee 10:16 But we sort of feel we can then go and eat an equivalent amount because we've just earned it.

Dr. Herman Pontzer 10:23 Yeah.

Dr. Rangan Chatterjee 10:23 But it sort of works the other way as well, doesn't it? In terms of if we have overeaten, we then think that, "Well, I can just go and, I can go for a double run tomorrow or a, or a extra long walk tomorrow to make up for it." But, but your research has shown that that just simply is not the case, at least for most of us.

Dr. Herman Pontzer 10:41 No, that's right. That's right. That's sort of the idea that you can run and earn your donuts, you know? Um, and it's a dangerous way to think actually, because when we, w- when you don't understand how clever the body is about sort of manipulating your metabolism, and you have this sort of simple view of, of how it works, then yeah, you, then you can make sort of silly decisions like that, like, "Oh, well, you know, I can have the box of donuts because tomorrow I'm gonna go on a longer run." Um, and actually the body doesn't really work that way. Uh, the body is, it's, there's a long-term kind of timeframe that your body's working under, sort of a couple weeks or even maybe a couple months, and it's paying attention to how physically active you are. And if you change that, if you, if you start your exercise program and you're, you're exercising more, you might lo- lose a little bit of weight early on. But as your body adjusts to that new level of activity, your total energy expenditure will sort of moderate and end up not a whole lot different than before you started. And now you think that you're earning all these donuts, right? Because you're, you've been really good, and you're doing all your exercises. But in fact, those donuts are gonna pile on because your ex- exercise expenditure isn't doing what you think it does. It's not total, raising the total expenditure per day in the way that you think you would expect it to.

Dr. Rangan Chatterjee 11:50 So how much does a typical Western man, a typical Western woman burn off-

Dr. Herman Pontzer 11:56 Burn off

Dr. Rangan Chatterjee 11:56 ... each day compared to, uh, the, the Hadza population?

Dr. Herman Pontzer 12:01 Yeah. So, um, so the biggest predictor of how many calories you're going to burn every day is how big you are, right? 'Cause I say we have 37 trillion cells, but obviously if we're bigger, we have more, and if we're smaller, we have fewer. Um, and so a, a typical, you know, U- US or European or U, you know, UK man- Burns about 3,000 kilocalories, uh, a day. And so that's about 11 megajoules if you prefer to do megajoules. Um, and that has mostly to do with how, how big you are, how many, how much you weigh, um, and particularly how much, uh, uh, fat-free mass you have. Fat, fat burns some calories. It's actually, it's, it's an active tissue. It makes hormones and that kind of stuff, but not as much. It's not nearly as active, um, as all your other tissues. So we kind of, fat is relatively quiet. So it's mostly your fat-free mass, uh, that determines how much you, you burn. Women, uh, in the US, UK, other parts of the industrialized world burn about 2,400 kilocalories a day. Um, and the difference is the, in, in the, in the amount of energy burned is because women are a bit smaller and, you know, tend to be a bit smaller, and also women tend to carry a bit more body fat. So for a given, you know, if you, if you have a man and woman step on the scale and they have the exact same total body weight, the woman probably will have actually a little bit less fat-free mass, 'cause women tend to carry a bit more fat.

Dr. Rangan Chatterjee 13:26 Yeah.

Dr. Herman Pontzer 13:27 Um, and therefore her expenditures will, we, we'd expect them to be a bit lower. Not because men and women are s- fundamentally different physio- I mean, they are ph- fundamentally different physiologically, but not because the expenditures are fundamentally different, just because the body compositions and sizes are a bit different-

Dr. Rangan Chatterjee 13:42 Yeah

Dr. Herman Pontzer 13:42 ... on average. Um, and then a Hadza man and woman, they, they tend to be a short statured group of folks. Uh, and so, you know, they're, they're a bit shorter th- on average than the typical US or UK, uh, man and woman. Um, so they actually burn fewer calories. Uh, women burn like 1,800 calories a day. Men are like 24, 25. They're all shifted down because they're smaller bodied. Uh, but once you accr- of course we, we account for body size and composition whenever, whenever we do these analyses.

Dr. Rangan Chatterjee 14:07 Yeah. I, I so want this point, the cen- one of the central points of your work to, to, to come through to people because I think it has... There's so many people who are, you know, struggling to lose weight. They are trying, they're torturing themselves, depriving themselves, punishing themselves all the time, and they're possibly doing it with the wrong equation in mind, right? So it's, it's, it's doubly tragic. It's [laughs] it's, A, it's not working, and B, it's like it's not working because actually you're putting in all this hard work and effort, and actually that's potentially not the right equation to be using. So if we just sort of break it down again, um, so we have, you know, let's say I'm a, you know, the typical Western man on average will burn off 3,000 calories per day, right? So 3,000 calories is what they're gonna use up, and you're saying a brain may use up, uh, 300 calories a day just to exist and do all the functions that we require off our brain, right? So there's 2,700 calories left on that sort of, um, on that very simple equation. So-

Dr. Herman Pontzer 15:18 Yeah

Dr. Rangan Chatterjee 15:18 ... you're making the case, I think, that our immune system, our reproductive system, breathing, lungs, liver, spleen, basically all the organs in our body just to do their job, they are chipping away at that. And so there's, um, a huge amount of calories that are being burnt, nothing to do with exercise, just to be alive and engage with life on a, on a daily basis. So then what happens? So for someone who then does go on a one-hour run, and that is or they think is going to be utilizing more calories-

Dr. Herman Pontzer 15:55 Yeah

Dr. Rangan Chatterjee 15:55 ... you know, what, what happens in the body to keep that at 3,000? You know, o- on, on one hand, you're, you're taking from here, but you're sort of pulling back somewhere else. Is, is that the, the idea?

Dr. Herman Pontzer 16:05 Yeah, that's right. That's right. And a, a couple things to be clear about. First of all, um, day to day you might still fluctuate in, in your expenditures, right? So if you always run 10 miles on Tuesdays and you sit on the couch all your other days, then yeah, on Tuesdays you'll burn more calories, right? Because your, your body can't adjust 24 hours. It, it doesn't adjust that quickly. It's more of sort of a, it, it's a lifestyle thing. Your body gets used to a lifestyle. So if you're the kind of person that's, that's running, you know, 20 miles a week versus the kind of person that's not, the person who's running 20 miles a week, uh, and your body's adjusted to that, is spending, well, 20 miles, so it's about, um, tw- uh, it's about 100 kilocalories a mile, right? On average. That's a good rule of thumb. So 20 times 100 is 2,000 calories a week. So 2,000 calories a week is being spent on exercise for you, and that means that person is spending 2,000 calories less on all the other stuff. And so, um, that's what's exciting for me as an evolutionary biologist is figuring out what does the body prioritize, right? And so we know that, that some of the things that the body's reducing ex- expenditures on, right, the things it's taking away from, are, are some of the really good things that exercise does for you. So if you look at that person who's running 20 miles a week, they're gonna have lower inflammation levels. But what is inflammation? Inflammation is actually energetically costly immune function that your body doesn't need to do, right? It's your innate immune function always on high alert when it doesn't need to be, and it's actually bad for you to have high background levels of inflammation.

Dr. Rangan Chatterjee 17:34 Yeah.

Dr. Herman Pontzer 17:35 Um, stress. If we look at people who are exercising, the, versus those who don't, the people who exercise have a sh- have, have a, a lower and shorter surge of things like epinephrine and cortisol in response to stress, right? Um, and that's so they're spending fewer calories, um, on that, on that stress response. And if you are, over the course of the day you're constantly being on high alert because, right, that's not good for you either. So actually the, the, the, the suppression of that stress response is probably really good for you. Um, people who exercise a lot will have, uh, healthy, I want to stress this, healthy but lower, uh, testosterone, estrogen, and progesterone levels on average. A bit lower, and that's gonna help you save energy too. So your body's basic- and that's, that's probably not the only thing that your body's doing.

Dr. Rangan Chatterjee 18:23 Yeah.

Dr. Herman Pontzer 18:23 Um, you might be making other sort of subtle adjustments about how you s- you know, do you sit rather than stand, that kind of thing. Um, so your body's kind of making all these adjustments, and th- that's how, that's, that's how you make the numbers work, that the people don't spend the 20-miler a week and the sedentary person don't have different expenditures overall because the 20-miler a week is spending less on these other things.

Dr. Rangan Chatterjee 18:44 Yeah. I, I love it. It just shows just how clever-

Dr. Herman Pontzer 18:48 Yeah

Dr. Rangan Chatterjee 18:48 ... and highly tuned our body's... Oh, it's really humbling actually to think we, oh, you know, we're smarter than our bodies. We'll, you know, we'll eat a bit more here, run a bit more over here. But our body's like, "H- Hold on a minute. We're, we're far cleverer than that." And I, and I really, I love the fact that it seems as though we can prioritize different functions depending on what's going on. So, you know, in y- in, in, in Burn, you write about n- not just the Hadza, you write about another, um, another

Dr. Rangan Chatterjee 19:19 population. It begins with T. I don't know how you pronounce it actually.

Dr. Herman Pontzer 19:21 Oh, the Tsimane. Yeah.

Dr. Rangan Chatterjee 19:22 The, the... How do you pronounce it?

Dr. Herman Pontzer 19:23 Tsimane.

Dr. Rangan Chatterjee 19:24 The Tsimane.

Dr. Herman Pontzer 19:25 Yeah.

Dr. Rangan Chatterjee 19:26 And I found it fascinating that, uh, and, that, that they, 70% of them have an active parasite infection in their guts.

Dr. Herman Pontzer 19:34 Yeah.

Dr. Rangan Chatterjee 19:34 And therefore I think you're saying that actually because there's that background level of infection and therefore inflammation, that the body is potentially diverting more energy towards the immune system and less to-

Dr. Herman Pontzer 19:48 Absolutely

Dr. Rangan Chatterjee 19:48 ... other parts of the body?

Dr. Herman Pontzer 19:50 Yeah. So the, so the Tsimane show this. There's a- another group where we've showed this even, uh... It's since the book has come out actually. This stuff is moving so fast, it's really fun. But there's a group called the Shuar, which is another, they're also an Amazonian... So the Tsimane live in Bolivia.

Dr. Rangan Chatterjee 20:03 Okay.

Dr. Herman Pontzer 20:03 The Sh- the Shuar live in Ecuador, and they're both sort of Amazonian r- rainforest, uh, populations. And, uh, s- the Shuar, uh, my, my post-doc at the time, Sam Aulucker, did this great study looking at children. And so we had Shuar children, um, who are very remote. They do a lot of hunting and gathering. They do a little bit of farming. But a, you know, subsistence sort of simple, traditional lifestyle. And they have a high, uh, pathogen burden too. You know, as you can imagine, if you live without, you know, any sort of modern medicines, uh, barefoot mostly, in, you know, in, in really remote rainforest environments, you g- get a lot of parasites, you get a lot of bacteria, so your, your immune system's always, um, active. Uh, and those kids, they have elevated basal metabolic rates just like we see with the Tsimane. But what's cool is w- with the Shuar population we've got them, we've got children, so we can actually measure their growth while they're, you know, 'cause, 'cause they're, they're kids. And h- Sam's able to show very nicely, if you look at, um, at the amount of immune activation, um, short-term immune function w- something we call, we measure with CRP, C-reactive protein, which are your body's first, like foof, you know, f- flush of immune response to a really ac- you know, an acute stress. Um, kids who have that, they grow less in the subsequent c- uh, subsequent couple of weeks. Kids who have these sort of long-term, you know, markers, uh... There's, there's different immune function markers that we can use to say, "Oh, that's a long-term infection," or, "That's a short-term response." The long-term responses are correlated nicely with kids' long-term growth. So the kids that are constantly getting the most immune hit, right, are backing off of their, they're backing off their, um, their growth. And, and sure enough when you measure expenditures, right, total energy expenditures, their total energy expenditures are the same as kids in the US or Europe, right? So these kids are playing with... In other words, these kids are all playing with the same energy budget. You all get the same number of calories and you can spend it however you like. And if you spend it on immune function, you've got less to spend on growth. It has to be that way, right? And, and sure enough, that's what we see. So those prioritization is just super interesting to watch happen.

Dr. Rangan Chatterjee 22:19 Yeah. Uh, it's, it's truly fascinating. And I mean, a little while ago you mentioned that the Hadza tend to be shorter stature-

Dr. Herman Pontzer 22:28 Yeah

Dr. Rangan Chatterjee 22:28 ... than, than let's say the typical Western population. Is some of this playing in there as well because of their lifestyles? Do you feel that maybe, you know, maybe we have... I don't know. You know, how, how would you sort of-

Dr. Herman Pontzer 22:42 Yeah

Dr. Rangan Chatterjee 22:42 ... how would you put that together potentially?

Dr. Herman Pontzer 22:44 Well, yeah, absolutely. I mean, you know, we, we don't know, um... But so height is a great example of a trait that has both a, a really strong genetic component, right? Tall parents tend to have tall kids. And a really strong environmental component, right? So there's... And it's this, it's not nature or nurture, or nature versus nurture. It's just those things acting together. Um, and so a population like the Hadza who tend to be short stature, they probably have a lot of, uh, gene variance that would, you know, even if they grew up here in the West, they probably would end up a bit shorter on average. So it's not just the environment, but I bet it's playing into it. And you know, probably the best example of this is, uh, something called the immigrant effect, uh, which is, was documented pretty well in the, you know, in the mid-1900s, which is that when you see, uh, you know, people who grow up, their parents grow up in a developing country, um, and without, you know, w- with a, without access to great medicines and without a- maybe access to great food, and with, maybe with a lot of physical stress in their lives. Their parents grow up and they're, they're relatively short. They move to a country that has better medicine, better nutrition, less work stress for the kids, and the kids are all, you know, a few centimeters taller than the parents on average. The immigrant effect. Um, and so that's been well documented in people from lots of different parts of the world. You come from an energy-stressed environment, you move into an energy-rich environment, and your kids get taller, right? Because your kids are spending less energy than you were as a kid on all these other tasks.

Dr. Rangan Chatterjee 24:10 The idea of a budget I think is brilliant. We've all got the same budget, so it's just where is your body gonna allocate the resources? It's like, you know, if you have a set amount of income, do you wanna spend that on a small house and a fancy car? Or do you want it on a, you know, do you want it on a big house and a, and a not so nice car? Or whatever. You know, it's, it's a, it's a-

Dr. Herman Pontzer 24:30 It's a trade

Dr. Rangan Chatterjee 24:30 ... useful way of thinking about the body, I think.

Dr. Herman Pontzer 24:33 Yeah, that's exactly right. And we talk, you know, in evolutionary biology, uh, we are talking about energy budgets all the time. That's kinda how we think about it, right? Um, and it's been fun too because for some reason, uh, in evolutionary biology, people got really comfortable talking about energy budgets in terms of, like, reproduction versus growth or maintenance, like immune function versus growth, and talking about trade-offs like that. Um, and then somehow even in evolutionary biology, activity was sort of this extra thing that could always get added on top, and you could always just fund that somehow separately. And I don't know w- how that thinking ever really took hold. Um, but basically my, my work is saying, no, activity is just another ac- You know, physical activity is just another activity that your body has to do that is just part of the mix. It's just part of the budget, you know?

Dr. Rangan Chatterjee 25:18 Yeah.

Dr. Herman Pontzer 25:18 And you kind of, you know, to expand or contract the budget much is hard. You know, you might, you might push a little bit. You might get a little, but not, not as much as you think you're getting because your body wants to kinda maintain a s- a s- the same budget no matter what.

Dr. Rangan Chatterjee 25:31 Yeah. Now, I think it's important that we're super clear. You're saying that exercising more, certainly in the long term, does not lead to us burning off more calories, but you're not saying we shouldn't exercise. In fact, you're saying quite the contrary, that it's incredibly important. And I love this bit in the book, which I'm just gonna read if you don't mind.

Dr. Herman Pontzer 25:52 Sure.

Dr. Rangan Chatterjee 25:52 "Those ancient adaptations have consequences for us today. Our bodies are built to move. In our modern, industrialized world, free of the daily demands of foraging for our foods, we need to exercise for our bodies to function properly. It's a legacy of our hunter-gatherer past." Why is it so important that we move our bodies?

Dr. Herman Pontzer 26:16 Yeah, so this is another, I think, benefit of taking an evolutionary perspective, and that is to understand that our bodies and our behaviors co-evolve, okay? So a really nice example of this, it is in fish, right? You ever heard the exam- that people talk about sharks? If sharks don't keep swimming, right, they drown. A shark can drown. Why? Well, because, um, you know, ancient fish, all anc- all ancestral fish, when they evolved gills, evolved the ability to pump. They have muscles on the side of their gills that allow them to pump the water past their gills. So they can, most fish can just hang out still and just slowly pump the water past their gills and, and they're fine 'cause they can ge- keep on getting fresh water, oxygenated water through their gills. Sharks and tuna and a couple of other, uh, sort of really active species like that, really physically active sh- species, they're, they're, they're swimming so much that, you know, evolution actually favored reducing and then eventually kind of eliminating, 'cause, 'cause why spend on energy if you don't ne- need to, uh, th- on that musculature? Because they're moving all the time anyway, they could just kinda open their mouths and the water just kind of streams past their gills. And so now, now, if you take that same fish and you don't let it move, it dies, right? So it's the behavior, the swimming all the time, and the anatomy, which is this gill pumping mechanism, or, uh, uh, gill pumping mechanism, co-evolving. And, uh, that's, it's a nice example that we can kind of all get ahold of. But it happens all over the place. This is, this is how evolution always works, is, uh, behaviors and anatomies co-evolve. In humans, right, a- again, we've been hunting and gathering for two and a half million years, and what does that do? Well, if you start hunting and if you start gathering on, in savanna landscapes where the food is, is scarce, you need to walk and just move a lot more to get your food. You have to, right? Food is farther apart to, to find. Um, animals will run fr- from you [laughs] . You know, they don't wanna get caught. Um, and so hunting and gathering just requires a ton of physical activity, and your bo- that, that's the behavior, and then the body be, a- adapts to that and gets used to that, and you just, your, your body ex- you know, you are born into the world with a body that expects to move, just like those f- you know, a shark is born in the world with a, with a, uh, gills that expect to be pushed through the water. Um, and now if we don't do that, if we rob ourselves of that constant activity that we'd normally get, um, yeah, bad things happen, right? Our physiology kind of expects that. And just like the shark that stop, stops swimming, bad things happen when we stop exercising 'cause every aspect, it's actually hard to find, I would challenge anybody to find a piece of your body that doesn't ex- that doesn't kind of, isn't contingent on that activity signal for normal function. It's, it kinda gets everywhere.

Dr. Rangan Chatterjee 29:11 Yeah. And I guess that then speaks to how do we, you know, how do we talk about physical activity to the population? You know, how do I as a medical doctor-

Dr. Herman Pontzer 29:20 Yeah

Dr. Rangan Chatterjee 29:20 ... talk about it with my patients? Because a lot of the time it is done around fat loss, weight loss. And I think there's two sides to that coin a little bit. I've seen a few of your, um, Twitter debates over the last few months-

Dr. Herman Pontzer 29:39 Have I been on that?

Dr. Rangan Chatterjee 29:40 ... uh, on this.

Dr. Herman Pontzer 29:40 Yeah, sure

Dr. Rangan Chatterjee 29:40 And, you know, it's quite a controversial topic as to, first of all, is exercise needed for weight loss? And therefore, depending on what your view is on that, how do we then articulate that message? So what are your sort of cur- having engaged in this for a few months and maybe several years-

Dr. Herman Pontzer 29:56 Yeah

Dr. Rangan Chatterjee 29:56 ... what is your current view on that?

Dr. Herman Pontzer 29:58 Yeah. Um, I think that we need to be honest with people. I think that that's, the best public health message is one that's gonna be accurate to the science, and I think the science says that exercise by itself is not a very good weight loss tool. And even exercise along with diet changes, exercise doesn't add a whole lot to the weight loss piece of it. Um-

Dr. Rangan Chatterjee 30:23 Is that in the long term? But because it, for, you're saying for a week or two, or three weeks-

Dr. Herman Pontzer 30:27 Yeah, you'll see an ep- yeah, sure

Dr. Rangan Chatterjee 30:28 ... you will get a benefit. You mean beyond that?

Dr. Herman Pontzer 30:30 Yeah, long term. So, I mean, this is, there's, there's great data on this that comes from all sorts of labs that aren't mine. So this isn't me speaking necessarily. This is, if you look at the long-term effects of exercise interventions, exercise alone- Um, the long-term expectation for weight loss is about two kilograms, right? So, um, that's great. If you're looking to lose two kilograms, that's perfect. But most people who are, are overweight or obese are looking to, to lose much more, and if you look at how much they're working, they sort of should lose much more, right? They're... The, the tons of calories they're burning. But it doesn't work that way because the body adjusts. Okay. So, um, I think, you know, uh, I sometimes my work gets, gets sort of I think mischaracterized as saying that exercise isn't important. I think that's, that's not what I've ever said.

Dr. Rangan Chatterjee 31:18 Yeah. I agree.

Dr. Herman Pontzer 31:18 Exercise is super important. Now, do we, do we exercise for weight loss? Um, I, I would say this. We don't exercise for weight loss, but you might exercise during weight loss for all the other benefits you get. But I think that if we wanna move the number on the bathroom scale, and if we wanna get fat loss to happen, then that has to be a diet approach, right? And, you know, when you go to any... Well, you know, look, I- I'm not a clinician, so I would defer to people who are in clinical practice like yourself. But somebody comes in and has a serious weight problem and, and we think that, you know, they... We look at their, their, uh, their blood profiles. We look at their blood pressure. We look at the direction things are going, and we say, "Look, this person needs to lose weight to, to get to a better place in terms of their health." There are a bunch of things you could prescribe, but wouldn't you make sure that you emphasize the thing that has the biggest effect, which should be, that, that's, that's diet.

Dr. Rangan Chatterjee 32:19 Yeah.

Dr. Herman Pontzer 32:19 Right? Um, and so I w- what I think is wrong, and that you see this in public health messaging all the time, is this equivalence of exercise and diet. That's what bothers me because that is not what the science says.

Dr. Rangan Chatterjee 32:33 Yeah.

Dr. Herman Pontzer 32:34 Right? So you say, "Well, you have to diet and exercise." And so if we say, if we say it like that, it sounds like maybe I'll just do one or the other, and I could pick. Or it sounds like maybe exercise and diet have the same effect 'cause one's energy in and one's energy out, and I could just decide to focus on one or the other, and that really isn't what the science says. The science says that diet is gonna do all the heavy lifting, and exercise to add on to that is fantastic and can do all kinds of good things, but it's the diet piece that's actually gonna change the number on the scale.

Dr. Rangan Chatterjee 33:03 Yeah. I really appreciate your perspective on that. Um, the last book I wrote was actually about sustainable responsible weight loss, and, you know, I, I quoted heavily your research in the exercise section. Um, and I think I said at one point, you know, do you need to move more to lose weight? No. Would I recommend it? Absolutely not, and, and I'll tell you why, and I think this is, I guess, where my clinician lens comes, come, comes in more than a scientific lens I guess or, or maybe, you know, slightly more biased towards what I, what I see with people, which is there's a lot of stress eating. There's a lot of comfort eating. There's a lot of eating when people are bored. You know, they know what they should ideally avoid eating too much of and what they should consume more of, yet despite the knowledge, they're still doing it. And what I found with exercise, particularly short bursts like, you know, I don't know, like 10 bicep curls every time you put a hot drink on in the kitchen, sh- uh, what I found is that there's no quicker way to boost people's self-esteem and their self-worth-

Dr. Herman Pontzer 34:12 Yeah

Dr. Rangan Chatterjee 34:12 ... than getting their body swimming. So I find although it's not necessarily there to help them burn off more calories, which it isn't, I find, especially if I make it manageable for that person in the context of their life-

Dr. Herman Pontzer 34:25 Yeah

Dr. Rangan Chatterjee 34:25 ... like I find it helps them engage and stay on track with kind of all the other things that I'd like them to do.

Dr. Herman Pontzer 34:33 That's wonderful to hear. Uh, that, that ex- makes a lot of sense to me. Um, I would say too, just potentially, uh, the, the advantage there is you haven't made exercise the, the reason that you're losing the weight.

Dr. Rangan Chatterjee 34:46 Yeah.

Dr. Herman Pontzer 34:47 Right? So if, and if you do, if you dis- if you disentangle those things, then you also disentangle the feeling of failure, um, that I think is a, a real danger of exercise-only weight loss approaches, which is if you're not losing weight, then you're doing the exercise wrong or you're not trying hard enough or it's somehow back on you that you didn't do the right thing. And I think that, you know, when, when we know that exercise alone is probably gonna end up in pretty modest, if any, weight loss at all, and all of it's gonna come early and you're probably not gonna see much after that, then you're kind of setting somebody up for the realization in half a year or a year later of this exercise program that, oh, this isn't really working anymore, and what is it? Am I doing something wrong, or is this even worth doing, right? And, and so when exercise gets tied to weight loss like that, I think that's a, a disservice to, to, to everybody.

Dr. Rangan Chatterjee 35:37 Yeah, and that's incredibly damaging for people's self-esteem because if they have diligently gone to the gym four times a week, pushed themselves, been on that treadmill for an hour four times a week, and they're not seeing the results, they do feel like failures, and what does that lead to?

Dr. Herman Pontzer 35:52 Lead-

Dr. Rangan Chatterjee 35:53 More comfort eating, [laughs] which actually compounds the problem. And I think your research, uh, has so many implications for so many different aspects of health. You know, for me personally, one of the, um, one of the most funnest kind of conceptual points in the book was this idea that, you know, we've spoken about on the podcast before how chronic unresolved inflammation is at the root cause of, you know, many of these modern degenerative diseases, heart attacks, strokes, Alzheimer's, all k- all, you know, rheumatoid arthritis, whatever it is. And I love this idea that because we have a, a fixed energy budget, if you were exercising more, then your body hasn't got as much, uh, budget left to give to inflammation. So it's actually gonna drop down that kind of unnecessary- chronic damaging inflammation, I think, well, that's a very powerful reason to move our bodies more because we're gonna reduce inflammation. So yeah, I wanna thank you for that, 'cause that was a brilliant perspective that I, that I absolutely loved.

Dr. Herman Pontzer 36:56 Well, thanks. Yeah, I mean, uh, when you stop thinking about exercise as just, you know, again, how many c- how many donuts have I earned, and you start thinking about all of the things that it's doing internally to regulate that budget, that's a lot more interesting actually, right? Now you're thinking about, "Wow, okay, gosh, what's exercise doing to reproduction? What's it doing to immune function? What's it doing to stress reaction?" And, and you can begin to sort of follow the calories, do the forensic accounting of it, like I was saying. Um, that's why it's so fun, y- you know, from, from just a pure biology point of view, but also, I think, um, powerful in terms of the c- the clinical potential there.

Dr. Rangan Chatterjee 37:31 And I guess just staying on weight loss for one, um, for one more point, and you did cover this in the book actually, this idea that when we move our bodies, that can have indirect effects on weight loss in the sense that it can regulate our hunger signals and our-

Dr. Herman Pontzer 37:47 Yes

Dr. Rangan Chatterjee 37:47 ... hunger cues a lot better, right?

Dr. Herman Pontzer 37:49 Yeah. And so this is an interesting thing, too. Um, so a couple of sort of other, you're right, a couple other things to add to the weight loss story. Exercise does seem to be really good for people to keep weight off. So when people have managed to lose weight, usually by diet, um, exercise has been shown to be a nice helpful tool for keeping the weight off. And so I think this has, again, that kind of regulatory aspect. It's helping you, either it's helping your sort of self-actualization about how much you eat, or it's helping your mood, or it's just helping your body, sort of the signaling in your body work better to match your intake at that new weight. Um, there's also this piece of it where, and this is kind of not well understood because I don't think we've focused on this enough. If you look at, at people who are really, really inactive, um, there's a great example of this. There's an old study in the 1950s done, um, at a jute factory, and, you know, thousands of workers. And this is one of the first sort of epidemiological studies to try to carefully look at, uh, activity and, and weight. And so what they did is they looked at people's jobs, of course, you know, thousands of people at this factory. There were lots of different jobs. And some of them were clerks, sort of pencil, paper pushers. Some of them were carrying bales of jute around. Some of them were like, had enormously physically demanding jobs of like cutting the bales and, you know. So you had this whole spectrum of how hard your job was. And at the very, very low end, uh, were the stall workers. And these folks, um, as I understand it, their job was to just sit. Just sit in the stall. You don't even, you're not even walking on the floor, you know, ticking boxes on your paper, on your clipboard. You're just, just sitting. Um, and then they looked at weight, at body weight. And the, really everybody's body weight was kind of the same from the pencil pushers, not the stall workers, but the, you know, the typical clerks up through the hardest working, you know, laborers. E- everybody's weight's more or less the same except the people who really just were plugged in a box and just sat all day. They had weight problems. Um, and they were overweight or obese, depending on, I don't, I don't know where they would fall in the classification. Um, and that says to me that if you completely take the exercise signal away, completely, then you might have this dysregulation issue where you're, you know, that's gonna lead to overeating. So in terms of, you know, exercise and weight loss, yeah, at the very, very low end of, of exercise, at the zero end of activity, there seems to be a real regulation issue there, um, that, that leads to overeating, and who knows what, what else was going on in those folks' lives. But, uh, but yeah, so the, you know, I think this is something, again, to sort of ex- explore, not, you know, so getting away from exercise as calories and getting towards exercise as regulation.

Dr. Rangan Chatterjee 40:37 I really wanna talk to you about your experience in Tanzania, because, you know, I've, I've read a lot of previous research studies on the Hadza. They seem to be studied a lot. Um-

Dr. Herman Pontzer 40:47 Yeah. Yeah. It's true

Dr. Rangan Chatterjee 40:48 ... there's a lot of, there's a lot of microbiome studies on them, which I've written about before. There's a lot of, on, you know, what is their fiber intake compared to, you know, typical Western industrialized populations. And I've always wanted to go and actually see the Hadza, see what, see what it's like, and you've obviously done that several times. So, you know, paint a picture for us. You know, you grew up in America. You're, you're on a plane. You, you know, w- what is it like? I mean, are you in an urban setting, then suddenly that just sort of stops, and Hadza land appears? You know, you know, so walk us through that a little bit.

Dr. Herman Pontzer 41:20 Yeah. Yeah, yeah. It is absolutely incredible. Um, so you know, you go and you, you, you fly into Kilimanjaro Airport, right? And you drive to a little city called Arusha, uh, which is, this is all in northern Tanzania. And the landscape is very, uh... You know, I grew up as a kid in Western Pennsylvania here in, you know, in sort of green forested rolling hills, and I was always, um, you know, um, uh, sort of taken by the nature shows and National Geographic that had the savanna. You know, that kind of yellowy grass, acacia, flat-top acacia trees. Um, you know, elephants and zebra and the whole thing. And I was just always just, uh, you know... I think a lot of kids feel the same way, which it just, just seems so amazing and cool. And so you land in Kilimanjaro and you drive out to Arusha, and you're driving, you know, you begin to drive into this savanna landscape, and it's just like, wow, you know? You, you really feel like you've landed in, um, someplace really different, uh, at least from where I grew up. And then Tan- you know, Arusha, it's a, you know, it's a little city, so you can get all your supplies. 'Cause everything that you're gonna do with, you know, during your work with the Hadza has to... It's a big camping trip, right? It has to all fit in the back of a Land Rover. Uh, and it, it has to be camping food, and you have to get water to bring with you 'cause it's really dry out there. And you have to get all the, all your stuff. Not to mention all your permits and everything, um, which all, it's very heavily regulated, as it should be. And so there's lots of regulations for, for doing the science and even just for going out there. And, and so that's, that's important, too. So we get all of our paperwork and we get all of our, uh, you know, supplies, and then you drive to another little town called Karatu, and it's smaller. It's half the size of, of Arusha, and it's, you know, a half day away. And then from there you kind of do your last pit stops, and then you're out to a little town called Mangola, right? And so... And there are some Ha- Hadza camps around Mangola, uh, if you wanna, if people wanna go and, and, and visit the Hadza. Sometimes that's where they go. Um, and then you're... If you're doing, you know, work with the folks who are really hunting and gathering out, uh, remotely, you're, you're even further past that, uh, more, you know, in, into sort of just into the space. There's no, there's no villages or anything like that. You're just sort of driving through acacia trees on, uh, on little dirt tracks or something like that. Um, and you just roll up in, in a Hadza camp. And so when I say you just roll up in a Hadza camp, you, you need to go with somebody who's been there.

Dr. Rangan Chatterjee 43:46 Okay. Okay.

Dr. Herman Pontzer 43:46 Right? You can't just parachute in. Uh, and for us, um, you know, well, I've been there a few times now, but I still, whenever I go, I go with, uh, my colleague Brian Wood, who's probably spent more time in a Hadza camp than he's spent in his own bed in the past. You know, more nights in a Hadza camp than in his own bed the last 20 years. Um, and, uh, you know, the- it's- You sort of, yeah, you kind of just show up. And, you know, there's no... You can't call ahead, right? There's no cell phone service. Some Hadza... Actually, some Hadza folks are getting cell phones now, um-

Dr. Rangan Chatterjee 44:20 Yeah

Dr. Herman Pontzer 44:20 ... because they're trying... Tanzania is trying very hard to put that part of the country on a, on a cell network. So, um, it's pretty limited, but some do have a cell phone that sometimes works. Uh, but you sort of still can't call ahead because it's not, you know, you can't depend on it. And, um, yeah, and, and so the camps are these, you know, maybe it's five, maybe it's 10 grass houses, um, kind of around a nice flat area. They always pick nice places. Um, and, uh-

Dr. Rangan Chatterjee 44:50 P- permanent grass houses? These kind of semi-permanent structures?

Dr. Herman Pontzer 44:54 Yeah. I mean, they don't... So they're, they're, they're rooted to the ground.

Dr. Rangan Chatterjee 44:57 Yeah, yeah.

Dr. Herman Pontzer 44:57 It's a dirt, it's a ground floor. The sticks are about, you know, as, from where, you know, kind of as big as your thumb to a bit bigger, and they bring them up and bring them to the middle, and the- they thatch grass through them.

Dr. Rangan Chatterjee 45:08 Wow.

Dr. Herman Pontzer 45:08 Um, and yeah, I mean, I don't know how... They, they last a while and then-

Dr. Rangan Chatterjee 45:13 Yeah, yeah

Dr. Herman Pontzer 45:13 ... I don't know what the time, what the, what the sort of shelf life is on a Hadza house. Maybe a year, something like that.

Dr. Rangan Chatterjee 45:18 I'm just trying to put myself in your shoes and-

Dr. Herman Pontzer 45:20 Yes

Dr. Rangan Chatterjee 45:20 ... just wonder what is that experience like for an American to rock up to this completely different tribe who's still living, you know-

Dr. Herman Pontzer 45:27 Yes

Dr. Rangan Chatterjee 45:27 ... relatively untouched by modernity. You know-

Dr. Herman Pontzer 45:30 Yes

Dr. Rangan Chatterjee 45:30 ... is, is there fear, and is, does that fear then get put at rest? You know, are they skeptical? What are, what are these Westerners doing here trying to study us and our energy expenditure and our, and our-

Dr. Herman Pontzer 45:39 Yeah

Dr. Rangan Chatterjee 45:39 ... microbiomes?

Dr. Herman Pontzer 45:40 Yeah.

Dr. Rangan Chatterjee 45:40 What does it mean?

Dr. Herman Pontzer 45:41 Yeah. No, absolutely. Um, yeah, I can still remember kind of, you know, the h- the door closing behind you and the Land Rover, punk, you know, and you're walking out and thinking, "What, what's, what's gonna happen?" And what's funny is, um, they, the, you know, the Hadza just couldn't be more generous and more gracious and wonderful. And, uh, they just kind of come up and they're smiling, "Hey, how's it going?" You know? Well, they, they say, they say, "Mtana na ma ega." That's, you know, there's, there's, uh, the greeting in Hadza, um, which you learn very quickly 'cause they make sure you know it, you know?

Dr. Rangan Chatterjee 46:11 Yeah, yeah.

Dr. Herman Pontzer 46:11 And you're, and you're... And it, everybody's super friendly. And I'm sure it has a lot to do with, with, uh, showing up with Brian 'cause they love Brian. Uh, and, you know, it's not a big community. It's only a few hundred people. So, um, Brian is, I think has probably met most of them. [laughs] Um, and they all know Brian, and they love him. So, you know, if you show up with Brian, it's like showing up with, uh, you know, with the Pope or something. I don't know. It's like showing up with a, with a rock star. Anyway, um, it, yeah, there's that moment of hesitation, and then they're just so friendly and nice that you just, you know, it kind of melts away. And then you're just amazed. You know, the, the guys are still walking around carrying bow and arrow, you know?

Dr. Rangan Chatterjee 46:48 Yeah.

Dr. Herman Pontzer 46:48 Women have just shown up with a, with a digging stick, you know, that they were using just a, 10 minutes before to dig tubers out of the ground. I mean, it is, it's very, um, it's, it's, it's so different-

Dr. Rangan Chatterjee 47:02 Sorry to interrupt. If you're enjoying this conversation, there's loads more like it on my channel. Please do press Subscribe and hit that bell. Now back to the conversation

Dr. Herman Pontzer 47:12 ... than anything that I, I'm used to, and the environment's different. Now, I grew up a lot in the woods, so I like that part of it. That's fine with me. The sort of remoteness of it doesn't, that doesn't affect me too much in terms of sort of being a shock 'cause I've done a lot of sort of, you know, backcountry camping and that kind of stuff. Um, but culturally, it's just so, so different, you know?

Dr. Rangan Chatterjee 47:32 Yeah.

Dr. Herman Pontzer 47:32 Yeah.

Dr. Rangan Chatterjee 47:33 You know, one of the things that I've enjoyed the most a- about your book, which I've gotta say is one of the best science books I, I've read. It's, it's so engaging. I... Y- you know, you've got science in it. Uh, you've got hard quality science in it. You've got stories in it. You've got the evolutionary lens, but it's these stories which, you know, they really, they, they, they lodge into my brain, and they don't sort of, they don't sort of leave it.

Dr. Herman Pontzer 47:58 Yeah.

Dr. Rangan Chatterjee 47:59 You know, one of them was, and I think I read this a few months ago when I got an early copy of the book, um, from your publisher, and I think you were there with Brian. I can't remember the chap's name, but I think he'd been unwell with dysentery and some gastro problems.

Dr. Herman Pontzer 48:14 Gastro problems. [laughs]

Dr. Rangan Chatterjee 48:15 And then offers you a bit of zebra. So can you tell us-

Dr. Herman Pontzer 48:18 Yeah

Dr. Rangan Chatterjee 48:18 ... a little bit about that story, but also what can we learn from that?

Dr. Herman Pontzer 48:21 Yeah.

Dr. Rangan Chatterjee 48:21 Because I thought it was really incredible.

Dr. Herman Pontzer 48:24 Yeah. Uh, there's, it seems like every day there's, there's a, a moment like this if it's, you know, um, a cobra in camp or, um, or somebody offers you uncooked zebra. Uh, you know, any- anything can happen. So that story is fun. So, um, that was... Forget the year. I think it was 2015, and we had gotten there to a Hadza camp, and it, as, as it happened, um, our, the what, first or second day that we got there, the guys, uh, s- shot a zebra And so, you know, but you're in an intact ecosystem out there. It really is, you know, it's, uh... So that's, that's a possibility that people might shoot a zebra, and so they did. And, uh, you know, z- zebra are big, uh, and so it got brought back to camp, you know, get in over people's shoulders and everything else. And, and then they slice it up into pieces. Uh, they eat all the organs pretty much immediately, and then the meat, which is just lots of meat on a zebra, they slice into sort of thin strips, and then they hang it from the trees to let it dry. And so the whole camp smells like a butcher shop for, uh, a couple days, you know? Um, and it's, uh, you know, it was, it was sort of three or four, maybe m- more along, probably more like a week in, people were still eating zebra, and we were going around. Uh, one of the things we do is, is we, we hand out, uh, little GPS units to either wear or sometimes they clip on a belt. Uh, 'cause we wanna know how they're using their landscape. That- that's one of Brian's big focuses is how they understand and use the landscape and, and that kind of traditional knowledge and trying to understand that because it's, they just, they know so much, and they see it in such a different way than we do that it's really just fascinating to see how they look at the landscape, how they use it. So we're, we give out GPS units to wear for the day, and that's, that's fine. And, um, and we go and find this one guy, Manasi, uh, and he had been just ba- ill, you know? He'd had like, yeah, dysentery or something. Who knows? It, some kind of diarrheal disease, uh, acute infection for a couple of days. And we're like, "Hey. How's it going? You feeling okay?" He's like, "Eh, you know, not really. My stomach still is gross and, you know, last night was bad." And, and he, like any other Hadza guy at his little camp area... He didn't have a family. He's by himself, so he just has his little sort of cleared area of ground, and he put some acacia thorns around the side so no animal walks up on him at night. He sleeps on the ground, and he's got a little fire smoldering, and he's kind of pi- you know, pushing it around with his, with his fingers. And he pulls out a little chunk of zebra meat. I realize, oh, that's, he'd been cooking it kind of for breakfast. And as we're talking, you know, he's like, "Yeah, man, I've been so sick, and just gross," and he starts tearing pieces apart. And I think, "Oh, he's gonna, he's gonna eat some breakfast." And he just starts, without even stopping, just offers, you know, "Here's, here's your zebra," you know?

Dr. Rangan Chatterjee 51:08 [laughs]

Dr. Herman Pontzer 51:09 Uh, and [laughs] and I thought, "Oh, God." Um, I, the zebra I didn't mind, but having it hand, handed to you by a guy who just described to you in, in some graphic detail about how bad his GI tract's been [laughs] , um, you know, and not, not a bottle of Purell in sight. Um, and so you take it and, you know, I look at Brian, and Brian looks at me. We're like, "Well," you know, you don't wanna be rude. So you pop it in your mouth, and it's like, uh, it's like, I, I think if you, if you pulled a piece of chewing gum off the bottom of a table in an, in an elementary school-

Dr. Rangan Chatterjee 51:41 [laughs]

Dr. Herman Pontzer 51:42 ... you know, and, and worked your way through that. I think that's about the texture and the, and the taste of it. Um, but you know, that's Hadza cuisine, and, you know, that's what you can learn from it. Well, first of all, um, yeah, you, you learn how thankful we can all be for modern medicine and an- and antibiotics and vaccines and all that kind of stuff 'cause my God, it's, it's a hard life out there. Uh, infectious diseases is, you know, is the number one killer. You know, little kids die all too often out there.

Dr. Rangan Chatterjee 52:09 Yeah.

Dr. Herman Pontzer 52:10 Uh, it's really... That, that's a, that's not fun at all. It's a sad piece of it. But, um, even adults are sort of dealing with stuff, you know, day to day, uh, that we deal with a lot less because we have clean food, and we have m- medicine. Um, but the other piece of it is, uh, you know, when people think about what paleo diets look like-

Dr. Rangan Chatterjee 52:28 [laughs]

Dr. Herman Pontzer 52:29 Yeah, right. Paleo diet doesn't look like aged grass-finished, you know, Angus steaks that you've, you, you know, nicely seasoned and are pairing with your beautiful, like asparagus or something. Like, no. Paleo diets are kind of... Most of us wouldn't wanna, wanna eat a real paleo diet, right? A real hunter-gatherer diet because it's, it's pretty, uh, just, uh, you know, it's just functional.

Dr. Rangan Chatterjee 52:53 Yeah. Yeah.

Dr. Herman Pontzer 52:53 It really just... It's just the... It's energy and protein, and, and it's not, like, delicious.

Dr. Rangan Chatterjee 52:59 Yeah. There's a couple of things in that story which really make me think. The first is, as you say, what i- what is a true hunter-gatherer diet? Uh, and this idea that, yeah, they, they got the, the zebra, um, so for a week, that's what they're eating. It's not like this idea... Well, please correct me if I'm wrong here, but this is something I really do feel is that we are seduced these days to thinking that every single meal we eat has to be phenomenally beautiful and tingle our taste buds. And I feel that-

Dr. Herman Pontzer 53:34 Yeah

Dr. Rangan Chatterjee 53:35 ... unintentionally, social media and all these gorgeous cookery books actually make this problem worse because you see, you know, y- a breakfast looking absolutely gorgeous, but you don't realize that it actually took five hours to style that. It's probably not even real food.

Dr. Herman Pontzer 53:50 Yeah.

Dr. Rangan Chatterjee 53:50 It's probably dried. It just... And the lights had to make it look so great.

Dr. Herman Pontzer 53:53 Yeah, right.

Dr. Rangan Chatterjee 53:54 And so you, you kind of feel, we sort of feel a lot that each meal has to be like that. It, it's something, you know, even in my own family, I, I'm very happy having the same thing for breakfast, lunch, and dinner if, if it's around. Whereas my wife will be, "Hey, babe, we had that, like, we had that for lunch. We had that last night. I'm, I'm having that today." And I, I, and it's really interesting 'cause that's, that is something I'm guessing is not what goes down in real hunter-gatherer land. It's like you don't really have that choice to... You know, you, whatever you can gather, whatever you can hunt is what you eat.

Dr. Herman Pontzer 54:28 Yeah.

Dr. Rangan Chatterjee 54:28 Right? Is that, is that, is that how it goes down?

Dr. Herman Pontzer 54:29 Oh, absolutely. Uh, there's, there, there aren't, like, breakfast foods and lunch foods and dinner foods in the Hadza camp. It's just food, you know? And breakfast is whatever was left over from last night. Um, I mean, the happiest Hadza kid I think I ever saw, the biggest smile on a face, was a kid walking through camp with a, the skull of a dik dik, a little antelope that his mom, I think, had given him, and it was all boiled out except for the eyeball. There's one boiled eyeball in there, and he had his dad's knife, which was like this huge. And he was, he's like walking through camp like prying the eyeball out and eating it-

Dr. Rangan Chatterjee 55:01 Oh

Dr. Herman Pontzer 55:01 ... you know? And he was so happy. He was like, you know, "Smile, everybody. Look at me, you know, I got the eyeball." Um, and I think that was the treat. That's your treat, you know? That's, uh, it isn't sort of the sugary breakfast snack, and it isn't, um, the, the lollipop at the end. You know, and it isn't the cookie. It's you-

Dr. Rangan Chatterjee 55:16 That's-

Dr. Herman Pontzer 55:16 "Oh, you get the eyeball. Good for you." Um, and you know, that's, I, I think the seduction is exactly the right word, that we have, um, w- you know, w- we've built these exotic diets for ourselves, and a lot of them are f- are full of really processed foods that we know push us to overeat. Um, but even the well-intentioned foods, I think, can do that because, you know, if your brain is evolved, uh, to eat a diet that's like the Hadza are eating, um, and now you take that brain and you put it in a world where you get all the delicious food you want all the time, uh, we shouldn't be surprised that our brains push us to overeat a little bit. And over time, that little bit adds up as a lot of, as obesity.

Dr. Rangan Chatterjee 56:04 Uh, and of course, it's very hard to overeat these kind of real unprocessed foods, right? Your, your brain sort of will tell you when, when, when you're full. I mean, did you see overeating of any sort that you could, that you could tell? Did you observe different sort of body shapes than you might see-

Dr. Herman Pontzer 56:22 Yeah. Uh, I've never... So we've seen a couple of w- I think, you know, w- so one of the things we do when we go to a Hadza camp is we measure everybody's heights and weights. That's kind of a baseline data point that we get-

Dr. Rangan Chatterjee 56:32 Right, right

Dr. Herman Pontzer 56:32 ... for everybody in camp. And so I've measured heights and the weights for, I think, you know, probably 1,000 Hadza at this point, Hadza men and women and kids. And, um, and I can remember seeing two women over the course of my, you know, 10, 10 years of working there on and off, that would be classified, I think, as overweight or maybe class one obese.

Dr. Rangan Chatterjee 56:52 Wow.

Dr. Herman Pontzer 56:53 So two in 1,000. Uh, and you know, the, who knows what their stories were necessarily. Um, they, they do occasionally, like, spend some time in the village and then come back. So I don't know how that obesity or-

Dr. Rangan Chatterjee 57:04 Sure, sure

Dr. Herman Pontzer 57:05 ... or, you know, overweight-ness, uh, you know, developed. I can tell you I've never seen Hadza women or men sort of doing what I would consider to be overeating, you know, what looks to my eyes to be overeating. I'll say this, they're not, you know, they're not like scrawny... You know, they're, they're, they're healthy, vital folks, so it isn't like they're starving. You know-

Dr. Rangan Chatterjee 57:23 Right

Dr. Herman Pontzer 57:23 ... they're always, there's always more food if they wanna go get it. Um, they never have the look or the s- they never talk about being, you know, starving for food. I mean, they're often, they'll, if you're, if they come by your camp... So we, we set up our little research camp kind of outside of theirs, just kind of stay out of their hair as much as we can. And if they swing through and we're eating something, then we alway- you always share. You have to share. So they're always happy to have a bite of whatever and, you know, so they're, they'll always eat. Um, but they're not starving. They're, you know, they're healthy weight and, uh... But yeah, it's really rare to see anybody-

Dr. Rangan Chatterjee 57:57 Yeah, yeah

Dr. Herman Pontzer 57:57 ... overweight.

Dr. Rangan Chatterjee 57:57 What, what sort of food? Did you have your own food, or would you consume Hadza food? Because, uh, what, what's really fascinating is when they do-

Dr. Herman Pontzer 58:03 Yeah

Dr. Rangan Chatterjee 58:03 ... rock by your camp and you offer them something, what are you offering them? And does it tingle their taste buds in a way that it's like, "Hey, you know, that's pretty cool. I want, want a bit more of that"?

Dr. Herman Pontzer 58:12 Yeah, that's a good question. Um, they, we offer them whatever we have, and so we always bring, we, we, y- you have to bring your own food. And so unless you've grown up in that environment, you will die if you just try to eat [laughs] any of y- whatever's there.

Dr. Rangan Chatterjee 58:25 Yeah, yeah.

Dr. Herman Pontzer 58:26 You know, I can't hunt, uh, a zebra. Uh, I'm not gonna do that. Yeah, so, um-

Dr. Rangan Chatterjee 58:31 [laughs]

Dr. Herman Pontzer 58:31 And you, and you can't eat theirs. I mean, if you show up and you're another f- we- we're a group of at least four each time because there's me and Brian and a couple of research assistants. We all, you know, we ha- we have Hadza, actually, um, uh, s- Hadza who have been in school and, and, uh, and wanna help out as research assistants. We hire Hadza, uh, community members to help us with the research, which is really fun. And so, you know, there's four of us at least, um, in, in our camp, and we can't impose on them and say, you know, "Feed us." Uh-

Dr. Rangan Chatterjee 59:00 Yeah, yeah

Dr. Herman Pontzer 59:01 ... it's, it's... They could do it, actually, but it would be hard. You know, it's just, we just don't do that. So we, we, it's like a camping trip for us where we, we bring all of our food in, you know, in, in cans or packets or whatever.

Dr. Rangan Chatterjee 59:11 Yeah.

Dr. Herman Pontzer 59:12 Um, which means that when they come by, you know, it's, it's, uh, maybe it's spaghetti and meat sauce or something like that, or be- rice and beans and, um... I mean, it's camping food. It isn't like it's-

Dr. Rangan Chatterjee 59:22 Yeah

Dr. Herman Pontzer 59:23 ... you know, delicious necessarily, but they'll eat whatever. And they're always like, "Yeah, thanks. Nice. Check you later." I mean, it doesn't, you know, they don't sort of-

Dr. Rangan Chatterjee 59:30 Yeah, yeah

Dr. Herman Pontzer 59:31 ... it doesn't blow their mind, I wouldn't say.

Dr. Rangan Chatterjee 59:32 No, no.

Dr. Herman Pontzer 59:32 But they like it. Yeah.

Dr. Rangan Chatterjee 59:34 Yeah, it's fascinating. The, the, the other thing I learned from that, or I took from that story about the zebra, is that he shared it with you.

Dr. Herman Pontzer 59:44 Yeah.

Dr. Rangan Chatterjee 59:44 And you've said that a couple times in this conversation. You always share.

Dr. Herman Pontzer 59:48 Yeah.

Dr. Rangan Chatterjee 59:49 And so-

Dr. Herman Pontzer 59:49 Yeah

Dr. Rangan Chatterjee 59:50 ... you know, going beyond the central thesis, I think there's a lot we can learn about human nature from your work. And, and I'm, I'm interested, you know, with, with so much division in the world, so much-

Dr. Herman Pontzer 59:59 Mm

Dr. Rangan Chatterjee 59:59 ... fighting, the, the message I get whenever I read about hunter-gatherers, whenever I, you know, through reading your, your work, Herman, is that there is, there's a sort of equality and there's kind of, there's that sharing is part of who they are. And I guess, does that make you think that's kind of who we are as well, but we've sort of lost it somewhere?

Dr. Herman Pontzer 1:00:21 Yes. Absolutely. Um, you know, in the discussion about ancestral diets and paleo diets and all this stuff, uh, there's all this focus on the hunting, uh, or the gathering, right? Is it, are we supposed to eat all animals? Are we supposed to eat all plants? And what gets completely lost is, um, that it's not hunting or gathering, it's hunting and gathering, right? Uh, and what do I mean by that? Well, the and part means you're sharing, because the and part means that some of us are gonna hunt, some of us are gonna gather, and we're gonna agree to come back to the camp at the end of the day and sh- and, and share.

Dr. Rangan Chatterjee 1:00:59 Yeah.

Dr. Herman Pontzer 1:01:01 And we are the only primate that shares like this. Uh, and we've been doing it for two and a half million years, as long as we've been hunting and gathering. So the, the... And it's the reason that we're so phenomenally successful as a species, right? Because when we share, we make more energy available for everybody, 'cause nobody goes hungry. Um, we widen the portfolio, broaden the portfolio of foods we can eat. Um, and so, and, and, and we also knit our communities together more tightly because we have to depend on this sharing. Um, and you know, the fact that, look, now that we're sort of slowly emerging from all the COVID lockdown stuff, what's the first thing that people wanna do, right? They, you know, they wanna go to a pub and they wanna share some chips and their beer, right? And they wanna have a barbecue, and they wanna have people over and share. I don't know how much, how wise all this is right away, but this is what people are, are itching to do.

Dr. Rangan Chatterjee 1:01:54 Yeah.

Dr. Herman Pontzer 1:01:54 Right? This is what people are, have missed, is to get together and share food. This is what humans do.

Dr. Rangan Chatterjee 1:01:59 Yeah.

Dr. Herman Pontzer 1:01:59 We're built to do this. Um, and the danger, of course, is that we're built to share within our group, right? We don't share it indiscriminately across groups. We share within our group. And so what people have manipulated, and politicians are very good at this, uh, is deciding who is not your group.

Dr. Rangan Chatterjee 1:02:19 Yeah.

Dr. Herman Pontzer 1:02:19 And you say, "Those people, those people are, are not our group, and they're the ones who are causing the trouble. We're gonna be a family. We're a family. We're real," you know, in, uh-

Dr. Rangan Chatterjee 1:02:28 Yeah, yeah

Dr. Herman Pontzer 1:02:28 ... in, in the US as it gets talked about. "We're the real Americans." Well, who the hell is everybody else? We're all Americans, right? If you're here in the US. So, um, it, it, but it gets talked about in these kind of divisive ways, and you take this beautiful thing that's really phenomenally important and unique about our species and, and kind of beautiful, this sharing and communality that we don't have in other species, and you weaponize it-

Dr. Rangan Chatterjee 1:02:50 Yeah, yeah, yeah

Dr. Herman Pontzer 1:02:50 ... because you say, you know, "Oh, that's only within our group and not across." And then we decide who the other groups are, and, and you can weaponize that, uh, really effectively. And it's, that's, that's the sad piece of it.

Dr. Rangan Chatterjee 1:03:00 How has spending time with the Hadza changed you individually? Yes, there's the science, game-changing science, which I think will have major implications all over the world. But on a personal level, you know, you go back to America with all this experience, having witnessed something that many of us only read about and imagine, but you've been there and seen it. You know, is there anything that you've put into your life on the back of that?

Dr. Herman Pontzer 1:03:25 [laughs] Yeah, I think, um, seeing how... It, it, it's, it's, it's the similarities and the common humanity across these cultures that I think is really, really the most powerful thing to bring home. Um, you go there, and we talked about how you, you know, you get out of the Land Rover and it's so exotic and different. Um, but the reason I love to go there now is the fact that when I see the Hadza kids running around camp, I see my own kids, right? When I see, um, a Hadza couple ar- talking about what they're gonna do that day or bickering or s- or laughing, I see my friends, you know, uh, talking, my, my f- my couple's friends talking about their families and their, what they're gonna do. And I see that same commonality, that, that same humanity throughout all of it. Um, and I think to see the same shape of a life, um, but in such different terms, it kind of gives you an outside view that you see the whole thing in a kind of, of outsider's view. And then you think, "Oh, wait, what if I did that to myself? What if I could look at my, at my own life from this kind of outsider's view, and I could decide what I liked about it and what I'd wanted to change?"

Dr. Rangan Chatterjee 1:04:39 Yeah.

Dr. Herman Pontzer 1:04:40 Um, you know, and, and I really, uh... It, it gives you some perspective. Um, you know, do you really wanna work seven days a week, or do you wanna make sure that you have time for your family? You know, do you want to, um, get three hours of sleep every night, or do you wanna sleep better and exercise more and be healthier into your old age? Uh, do you want to... You know, what's important? And what's important for the Hadza are, are those personal connections that they nurture throughout a life because that's who they're with. They're in that social mix every day. There's no, you know, um, ge- you know, Billy's gonna go for the g- the brass ring and check out and, and work, you know, work himself to death. It... W- No. People don't do that. Like, why, why would you? Um, and so I think that, uh, that perspective has been helpful-

Dr. Rangan Chatterjee 1:05:28 Yeah

Dr. Herman Pontzer 1:05:28 ... for me to kind of slow down, calm down, nurture the, the, the personal connections. That's been useful for me.

Dr. Rangan Chatterjee 1:05:36 Yeah, I love that. Such profound wisdom, Herman, uh, in what you said there. Something I think we can all learn from. Uh, just as we draw this conversation to a close, one thing I, I really wanted to briefly touch on relating to your, uh, work on energy-

Dr. Herman Pontzer 1:05:50 Mm

Dr. Rangan Chatterjee 1:05:50 ... and we're, we're only scratching the surface here. The, the, the book has got so much stuff in it that I think frankly anyone would enjoy reading it. Really is that, that compelling a read from start to finish. But there was this bit there where two things re- relating to that, which is doesn't matter how far you walk or run or how fast you do it, you're gonna burn off the same amount of calories. You, if you run one mile in, let's say, 15 minutes, or you run it in eight minutes, you're still gonna burn off the same amount of calories, which I found-

Dr. Herman Pontzer 1:06:23 Yeah

Dr. Rangan Chatterjee 1:06:23 ... if I've got that right, I found that fascinating. And the other thing was when you compared the different movements and how walking, w- w- we're evolved to walk. It's so efficient to walk. We hardly burn off anything. Running as well-

Dr. Herman Pontzer 1:06:36 Running

Dr. Rangan Chatterjee 1:06:36 ... but you said swimming and how costly that can be. So I just wonder if you could just sort of touch on those points just to finish off.

Dr. Herman Pontzer 1:06:43 Yeah, so this is, this is fun for me because my, my earliest graduate student work was on the biomechanics of locomotion. So, you know, the walking, running, climbing. We still do some work like that in my lab. Um, and it's just a really fun game to kind of reverse engineer the body and think about yourself as, as this machine moving through space. And like any machine, we might be interested in how many calories, how much energy it burns to go a mile. Um, and you're exac- absolutely right. So, so running- You know, the, the mechanics of running, you're like a pogo stick. You're bouncing along, thunk, thunk, thunk, thunk, thunk. And the, just the mechanics of that mean that you're gonna end up burning about 100 kilocalories a mile. Depends on how much you weigh, because if you're heavier-

Dr. Rangan Chatterjee 1:07:25 Yeah, yeah

Dr. Herman Pontzer 1:07:25 ... then each thud of the pogo stick is, is more w- more weight, more energy. But so most of us, about 100 kilocalories a mile. Walking, um, when you walk you do this amazing thing, which is that you turn your body into a rollercoaster track, right?

Dr. Rangan Chatterjee 1:07:42 [laughs]

Dr. Herman Pontzer 1:07:43 And so you're going up the hills and down the hills, and up the hills and down the hills, right? So, uh, in a rollercoaster, right, it gets you up that first big hill, and then it lets you go, and then you use the energy from being at the top of that first hill, you use the energy to go all the way through the whole thing into the end, right? And th- you need- you use the same trick when you walk. So as you walk, um, you kinda don't notice it, but as you, your, your heel hits the ground, and you kind of vault up over your leg, and that's the top of the hill, and then you shh-shh through the middle. You know, in each step you're doing this rollercoaster thing, and it's so remarkably efficient-

Dr. Rangan Chatterjee 1:08:19 Yeah

Dr. Herman Pontzer 1:08:19 ... uh, that you burn about, it's really only, like, half the calories of running. It's incredible how much energy you save, and we're the only animal that walks with that particular kind of a ga- There are other two-legged animals, of course, but, um, we're really, w- we're, we're special in, in how remarkably efficient we are. Um, and so that, that's really fun. But yeah, you still move up and down, right? Which is why-

Dr. Rangan Chatterjee 1:08:44 Yeah, yeah

Dr. Herman Pontzer 1:08:44 ... I'm, I'm sitting here drinking my coffee, uh, sitting down so I don't have to have a top. But if you go to your local, you know, tea shop or coffee shop and you walk out the door, you gotta put the lid on first.

Dr. Rangan Chatterjee 1:08:54 Yeah. [laughs]

Dr. Herman Pontzer 1:08:54 'Cause if you don't, you get splashed all over the place, 'cause you're actually on a rollercoaster. You don't even know, right? But you're on this rollercoaster the whole time.

Dr. Rangan Chatterjee 1:08:59 Yeah.

Dr. Herman Pontzer 1:09:00 Um, and then swimming. Well, swimming, we're not evolved to be very good swimmers, and so w- th- there's no special bit there. Uh, you're just in- but instead of, you know, just sort of pushing yourself off of solid ground, now you're dragging yourself through the water. Well, that's, that's hard. And so, you know, I, I don't know off the top of my head wh- how the numbers compare, but it's a lot more calories to swim, um, a mile than it is to walk or run it.

Dr. Rangan Chatterjee 1:09:27 I think climbing as well, is that right? Climbing was more-

Dr. Herman Pontzer 1:09:29 Yeah

Dr. Rangan Chatterjee 1:09:29 ... than running and walking as well?

Dr. Herman Pontzer 1:09:31 Yeah, so that's a really fun one. So climbing, and we just published a paper on this. Oh, sorry, we just have it, it's in press. It's not even out yet. Um, uh, it doesn't matter if you're built like a monkey, 'cause people have measured this in monkeys, or if you're built like us or anything, uh, to climb, to, to get your body to climb, let's say 10 meters up a tree, um, uh, it's the same amount of energy per, per kilogram of body weight no matter how you're built. Uh, so you're, you know, if, if you're, um, if you've had a, a mechanics cl- You're, the high school students listening to this will be familiar with this, which is that if you wanna calculate how much work was done, how much potential energy was gained when you go from the ground up to the top of the tree, right? It really is like a textbook physics problem, which is kind of fun. Uh, you take the mass of the thing, which is your body weight, you multiply it by gravity, and you multiply it by the, the, the vertical number of meters climbed, and that's how much potential energy in joules that you've climbed. Uh, and, um, it turns out that all muscle is kind of equally efficient at doing that work, and so kinda doesn't matter how you're built and how you do it, it's the same calories to go up to the top of that tree, again, whether you're built like me or whether you're built like a monkey or whether you're built like some other thing, you know, a lizard or something else that climbs. Isn't that funny? It's one of those, uh, like universals of, uh, of, uh, of, of life on Earth.

Dr. Rangan Chatterjee 1:10:55 Yeah, for sure. Uh, there's so much interesting stuff that you, [laughs] that you talk about or write about, and, uh, we, we barely scratched the surface. Herman, I really appreciate you making time to come on the podcast today. I've really enjoyed speaking to you. Uh, the podcast is called Feel Better, Live More. When we feel better in ourselves, we get more out of life, and I wonder if you have, on that theme, any sort of closing notes, closing thoughts perhaps? You know, your research really is profound. It's game changing. You know, have you got any sort of final words of wisdom? You can put it all together so people can start to improve the quality of their lives.

Dr. Herman Pontzer 1:11:33 That's a, a, a hard question, because I think it's so personalized, right? What you need to do for you is gonna be, it's, it's, it's unique to your own situation. But here's what I would suggest. Start by getting outside. I think that's hard to go wrong. Get outside. If you get outside, what are you doing? You're away from your refrigerator, for one thing. You're probably moving. That's another good thing. Um, if you're getting outside with friends, that's even better, right? Fresh air, vitamin D, uh, it's hard to go wrong. Uh, people in the industrialized world spend about 90% of their life inside, either inside a house or inside a car, and we aren't evolved to do that. Um, and so, you know, we could talk about the details of a diet or the details of an exercise program, but a good place to start is to just get outside more.

Dr. Rangan Chatterjee 1:12:21 Herman, thanks for joining me on the show, and I hope we get a chance to do it again at some point in the future.

Dr. Herman Pontzer 1:12:26 Thanks so much for the conversation. It was really fun. [outro music]

Dr. Rangan Chatterjee 1:12:28 If you enjoyed that conversation, I think you're going to love the one that I had with Professor Tim Spector all about foods. It's right there, so give it a click and let me know what you think.

Speaker 1:12:38 But if you snack a couple of hours before a meal, your metabolic response to that meal is poorer than if you didn't snack.

Dr. Rangan Chatterjee 1:12:46 Okay, just say that again, 'cause I think that's really important