The Evolutionary Truth Behind Why Exercise Feels So Hard with Daniel Lieberman

James Hill:
Welcome to Weight Loss And, where we delve into the world of weight loss. I'm Jim Hill.

Holly Wyatt:
And I'm Holly Wyatt. We're both dedicated to helping you lose weight, keep it off, and live your best life while you're doing it.

James Hill:
Indeed, we now realize successful weight loss combines the science and art of medicine, knowing what to do and why you will do it.

Holly Wyatt:
Yes, the “And” allows us to talk about all the other stuff that makes your journey so much bigger, better, and exciting.

James Hill:
Ready for the “And” factor?

Holly Wyatt:
Let's dive in.

James Hill:
Here we go.

Holly Wyatt:
Jim, we talk a lot about physical activity on this podcast. Some people may say maybe we talk too much about it. It's one of our favorite topics. In our book, Losing the Weight Loss Meds, increasing physical activity is one of the three pillars for successful weight loss maintenance.

Holly Wyatt:
But the reality is, many people struggle to incorporate regular physical activity into their daily lives.

James Hill:
Yeah, Holly, and that raises an interesting question. If physical activity is important for health and weight management, Why is it so hard? So I'm really excited about today's episode because we're going to look at that question through a completely different lens. We're going to talk about what our evolutionary history tells us about why we exercise or avoid exercise and what it really takes to build physical activity into modern life in a way that actually sticks. I am so excited to introduce our guest, Dr. Daniel Lieberman. I have never met Dan, but I have read his stuff with great interest. So I have so many questions for him. He is professor of human evolutionary biology at Harvard University. He's a paleoanthropologist. Now, Holly, you know what that is, right?

Holly Wyatt:
No, but we're going to find out.

James Hill:
We’ll ask him to define it. He studies the evolution of human physical activity and its relevance to health. His research explores why we walk, run, and exercise the way we do. And importantly, what happens when modern lifestyles collide with ancient physiology. He's the author of The Story of the Human Body and Exercised. And I just read Exercised, and it's a great read. It's an easy read, really, really good stuff. These are two influential books that challenge many of our assumptions. We like that, Holly, challenging assumptions, about fitness, metabolism, and health. His work reshapes how we think about physical activity and offers powerful insights into how movement supports long-term weight management and overall well-being. Dan, we're thrilled to have you with us on Weight Loss And.

Daniel Lieberman:
Happy to talk to you. I've always been following your work, too, so it's reciprocal.

James Hill:
So, first of all, what's a paleoanthropologist?

Daniel Lieberman:
I just study human evolution. It's just a fancy way of saying that I study human evolution.

Holly Wyatt:
Wow. Tell us kind of what is that central argument that you talk about a lot in your books, the idea that maybe humans never evolved to exercise. Tell us a little bit about that.

Daniel Lieberman:
Well, let's, first of all, begin with a definition. So we all talk about, we all know what physical activity is. It's just, you know, gesticulating, moving around, doing the dishes, whatever. Exercise is a particular kind of physical activity. It's voluntary. Well, I define it as discretionary. So you don't have to do it, but discretionary, voluntary physical activity for the sake of health and fitness. And you have to realize that no animal exercises except for humans. And until recently, no human exercised because we evolved to be very physically active creatures. In fact, we evolved to be way more active than our relatives, the apes. So chimpanzees are basically couch potatoes. And during our evolutionary history, we evolved to become much, much more physically active in order to get food. But we always struggled to get enough food. And the way we got food, there was no Uber Eats or supermarkets. We had to go out and get it by walking long distances and carrying it and running and digging and all those sorts of things. And so we evolved to be physically active and to get our food and not be somebody else's food.

Daniel Lieberman:
But because food was always limited, we never evolved to do what I do, which is go for a completely unnecessary five-mile run in the morning. Or in my basement, I have a whole bunch of weights. I bought pieces of heavy metal whose sole job is to be lifted, right? I mean, tell that to one of our ancestors from a few generations ago, and they think we're completely mad, right? And in fact, because people were energy limited, but had to be very physically active. I mean, in my research, we measure physical activity levels in non-industrial populations. In fact, it's disadvantageous to exercise because you're actually spending energy that could go towards your family and towards reproduction, which is what natural selection cares about. So I entitled the book Exercised because what we do is we tell people that they're lazy if they don't exercise. There's something wrong with them if they don't exercise. But in fact, it's an instinct not to exercise. When you go to a shopping mall and you see an escalator next to a staircase, right? I mean, there were no staircases, no escalators in the Paleolithic, but it's an instinct to take the escalator because it's an instinct to avoid discretionary, unnecessary, or unrewarding physical activity. And so we make people feel shamed and blamed for not exercising. So we make them exercised about exercise. So that's why I entitled the book that way.

James Hill:
You say in your book, I think you say, we're born to rest, not to run.

Daniel Lieberman:
Well, we're born to do both. But, I mean, we are born to run. I mean, I published a paper in Nature entitled that, we evolved to run in order to hunt. But we didn't evolve to run marathon. Nobody evolved to stand on one line and run 26.2 miles as fast as possible to another line, just so they could wear a medal. That's a very modern behavior.

James Hill:
So a lot of what you're talking about is how the modern world has changed in a way to, you know, kind of engineer physical activity out of our lives. One of my colleagues put it, we used to pay people to exercise because you had to be active during your work. And now you have to pay to exercise to join the gym and everything. That's a huge change.

Daniel Lieberman:
That's right. And it's actually still not true for most people on the planet. You know, I work in places like Kenya and Rwanda, etc., where people still have to work extremely hard to get by. So it's really only in this very weird bubble of a modern world that we've created in places like the United States, where we have basically made it not only optional to exercise, sometimes it's difficult to exercise. People who live in environments where there's no sidewalks or playgrounds, you know, in the hospital, I go, there's no staircase. I have to take the elevator to the third floor to see my doctor. It's crazy, right? So we have engineered it out of our lives, exactly. And we pay people to do it, or we pay people to do it, and then we sit in our couches and we watch them do it.

James Hill:
Yes, exercise as a spectator sport.

Daniel Lieberman:
Yeah, exactly.

Holly Wyatt:
So, tell us a little bit about sitting. We don't just talk about exercise now. We talk about sitting maybe being the next smoking, the idea that sedentary behavior can be just as bad for us, a problem for us, independent even of physical activity. So, what does your research say about sitting and the hunters and gatherers?

Daniel Lieberman:
So this is actually researched by a former postdoc of mine, Dave Raichlen, who's at USC. But I certainly observed it myself because I've spent some time with hunter-gatherers and certainly with a lot of subsistence farmers.

Daniel Lieberman:
But, you know, we say our chairs are out to get us and sitting is the new smoking, et cetera. But sitting is a completely normal, natural thing to do. And it turns out, that hunter-gatherers, when they're not active, guess what they do? They sit, right? Like my dog who sits, you know, whenever she can. Sitting is a completely normal behavior, and we shouldn't, again, make people exercised about sitting. That said, it is true that if you sit all day long, and then you go home, and you, you know, you sit on your car on the way to work, and then you sit all day long in your desk, and you sit on the way home, and then after dinner, you sit during dinner, and then you sit after dinner, yeah, you're going to get into trouble. So, and so if you look at the data, the effect of sitting on health is primarily leisure time sitting, not work time sitting. Those are the studies. And furthermore, there's another big difference is that, you know, like I'm sitting now in a chair, you can see that I have a, you know, a backrest on my chair, actually my big backrest on this chair, but I'm using absolutely no muscles to sit. But chairs with backs are actually a recent invention. So we now sit in a much more inactive way than we used to sit. People used to have to spend some, they used to sit on stools or on the ground, right? And so we have no muscular effort right now when we sit. Of course, even turning on those muscles a little bit has effects on our metabolism, just, you know, you're using up sugar and etc.

Daniel Lieberman:
And the other thing is that we sit now for long bouts of time, right? So even though a hunter-gatherer and a typical, you know, westerner sit about the same amount of time a day, about 10 hours, we sit for long bouts for hours and hours at a time. Whereas if you sit in a hunter-gatherer camp, I can tell you that people are getting up and down and up and down and they're rushing after babies and they're putting something on the fire. So nobody sits for more than like 10 or 15 minutes at a time. And again, turning those, those just short interrupted bouts mean that you're turning on the metabolism of your muscles and having an enormous effect on your overall body's metabolism. So it's not so much how much we sit, it's the length of time we sit, how we sit, and of course the fact that we sometimes aren't physically active, which means that you're sitting even more.

James Hill:
The screens help that, right? In our leisure time, we now have our phones and our computers and so forth that allows us to be entertained for very long periods of time being completely sedentary.

Daniel Lieberman:
Absolutely. Yeah, it's getting worse and worse and worse. And our bodies are just not adapted for that. That's what we call an evolutionary mismatch. So I define a mismatch as a condition that is either more common or more severe because our bodies are inadequately or imperfectly adapted to that novel condition. And so while it's normal and natural to sit, we're poorly adapted to sit basically all day long for long periods of uninterrupted bouts. And there are many other mismatches too, but that's a big one.

Holly Wyatt:
Let's switch a little bit over to weight loss and exercise. One of the biggest beliefs out there in weight management is that exercise is a tool for weight loss. We don't 100% agree. Jim and I think about exercise being primarily for weight loss maintenance. But still out there, people think, I've got exercise to lose weight. Your research complicates that. What does the evidence actually show?

Daniel Lieberman:
Well, the reason I laugh is that it's a big debate going on right now. And not everybody agrees. So you may have seen articles recently saying that you can't lose weight by exercising. Because when you exercise, you actually lower your basal metabolic rate, your metabolic rate when you're basically doing nothing, when you're just sitting or lying in bed. As a result, there's sort of compensation. Other forms of compensation that have been proposed are that if I go for a run in the morning, then I'm going to be less likely to move around the rest of the day. What we call non-exercised physical activity, or sometimes people call it non-exercised thermogenesis. Neat. But either way, it doesn't really matter what you call it. And the other hypothesis is that when we exercise, I go for a five-mile run, I go home, and because I'm so hungry, I now eat a big donut, which is more energy than the energy I spent exercising. And well, it's kind of hard to test all these hypotheses. We can more or less, discount the last one. So, it turns out that, yes, people do get hungry after the exercise, but study after study shows that they don't completely compensate for it. So, we can cross that one, not entirely off the list, but mostly off the list.

James Hill:
Yeah, we've talked about John Blundell's work there. That's very, very powerful there.

Daniel Lieberman:
There you go. So, the other is the activity compensation, and that does occur to some extent. Um, again, but it depends on their dose, right? How much exercise you do. So people who, uh, for example, there's a study that I was involved with, um, where people ran across, they ran a marathon every day across the United States. Um, well, they took, they took one day off a week. But other than that, they, they ran a marathon every day across the United States. And guess what? Uh, when they weren't running a marathon, um, they were so tired. They basically sat like vegetables in their chairs for the rest of the day, because they had to conserve their energy to run the next day. Yeah, of course, that's extreme, right? But there is evidence that there is, and there's plenty of other studies which show that there's what we call behavioral compensation. The final one is the real kicker. So it's well known, and my lab has done studies, and plenty of other lab studies have done studies, where when you exercise, you raise your metabolic it great for a while afterwards. Some people call it afterburn. The technical term is EPOC, excess post-exercise oxygen consumption. But we can call it afterburn for, I guess, a show like this. And we know that that goes up for a little while, right? It depends on your dose. So if you do a lot, it'll go up just a little bit for just a short period of time. You do a lot of exercise, it'll go up more and for longer. And we also know that the majority of that excess energy of your metabolism is not just to replace the energy you spent, it's doing something else.

Daniel Lieberman:
And I think that's the repair and maintenance mechanisms because exercise is stressful. You produce reactive oxygen species, these little unpaired molecules with unpaired electrons that can damage DNA in cells. You produce cracks in your bone and your muscle. You generate heat, which kind of damages protein. I mean, there's all kinds of stresses. I mean, every single tissue in your body is stressed by exercise, and you have to repair that. So exercise turns on, I think, for every single one of these forms of stress and damage, exercise turns on a wide range of repair and maintenance mechanisms, but those cost energy. And so for a while after exercising, you have this, you know, you're spending energy to kind of keep your body. And the good news is that it seems that we not only repair and maintain, we kind of overshoot a little bit. And the analogy I often use is like, if you spill coffee on the floor and then you clean up the floor, it's often cleaner after you spilled up the coffee because you end up doing a slightly better job. And if you didn't do that, well, your exercise would be bad for us. We'd die younger if we didn't repair all that stuff, right? So, we've long known that there's this temporary increase. And some people have argued that that actually depresses your metabolic rate. And we just published a paper, that's why Dr. Hill just emailed me, reviewing all the evidence in gruesome detail. And we have more studies coming out, that that's actually turns out not to be true.

Daniel Lieberman:
That people who exercise do not lower their resting metabolic rate. They are actually, they're temporarily raising it. And so don't worry about that. However, that doesn't mean that, I know I'm going on for a long time, but you asked a big question, so that's okay if I can go on.

James Hill:
Yeah, go on.

Daniel Lieberman:
But that doesn't still answer the question about how useful exercise is for weight management.

Daniel Lieberman:
And as you pointed out, there's two components to weight management. One is losing weight, and the other is preventing weight gain or weight regain. And they're very different. They're not just like the same thing.

James Hill:
I love this, Holly. He's singing off our page.

Holly Wyatt:
Not everybody thinks this, believe it or not. I mean, we are 100% on board, but some people think it's just one long thing, the same thing.

Daniel Lieberman:
Oh, that's nonsense. Of course it's silly. Well, let's talk about why it's not true, right? Okay, so the first is that there's more to exercise than simply the calories that you spend.

James Hill:
Yes.

Daniel Lieberman:
When I exercise, I don't only just spend energy, you know, like if I went from, I haven't had a chance to go running today yet, but I will this afternoon. But anyway, when I go for my run this afternoon, I'll probably do like a five-mile run. I'll spend about 500 calories, right? But I'm also going to change my hormones, right? My insulin levels are going to go down, and my insulin sensitivity is going to change to carbohydrate. My glucagon levels are going to go up. My cortisol levels are going up. There are all kinds of endocrine responses to the exercise. And, you know, your body isn't just like a simple bank where you put in money and you take money out.

Daniel Lieberman:
All those shifts in how energy is stored and used and released is all mediated by hormones. And so you can't just think of it purely as like a bank with withdrawal and deposits, right? It's a little bit, it's more complicated than that. So it turns out that, yes, if you exercise and there are plenty of studies that show that you can lose weight when you exercise, but you have to do a lot and you have to do it consistently. And so, you know, the typical World Health Organization minimum that we all, I'm sure, you know, we all talk about all the time is the old 150 minutes a week of moderate exercise, you know, 150 minutes a week of, which is basically 21 minutes a day of walking. You're not going to lose weight walking 20 minutes a day, or at least if you do, it's going to be so small, it's going to be swamped by other things. However, studies show that if you have higher doses, you can lose weight. You're not going to lose a lot, and you're not going to lose it fast, but drip, drip, drip, drip, you can lose the weight. And these are gold standard randomized control studies where they do it. But here's another important point, is that you have to look carefully at these studies because there's a difference between what we call efficacy and effectiveness.

Daniel Lieberman:
Efficacy is how well something works in ideal conditions, like a randomized control trial, where you have people and you tell them how much to exercise, and you have a supervisor who's there to actually make sure they do that exercise and follow the prescription versus unsupervised exercise where they might not necessarily do that. And so effectiveness is how well something is in the real world, whereas efficacy is in ideal conditions. And study after study after study show that when you tell people to exercise, they usually, despite their intentions, they don't always make it, right? And so the studies in which have had low effects of exercise on weight have been studies where it's not the efficacy that's in question, it's the effectiveness. Because if you actually look at the adherence data, you know, how much people actually did it, it's terrible.

Daniel Lieberman:
People just, you know, very small amounts of exercise, people don't do it. So studies that have solved this efficacy versus effectiveness problem show that 300 or more minutes a week of exercise help people lose weight. And it's a dose response effect. The more you do it, the more weight you lose, as you might expect. But again, you have to be very careful looking at these studies. And more importantly, as we were talking about earlier, weight loss is not the same thing as preventing weight gain. And the dose for preventing weight gain is lower than the dose for weight loss. So you don't have to do as much exercise to prevent weight gain as you do to lose weight. So 150 to 300 minutes a week actually is pretty good for helping people prevent weight gain. And again, we kind of know why. Again, it's not just the calories, it's because if I go for a run, or a walk for that matter, and I eat a doughnut afterwards, right?

Daniel Lieberman:
I'm going to get actually less of an insulin rise from eating the same donut if I'm just even moderately physically active. And that means I'm going to store less of that donut as fat, and I'm going to also have less insulin to keep that fat in my cells. So there's an endocrine effect that's not captured simply by measuring calories. So to sum it all up, we have good data that with high enough doses, you can slowly and gradually lose weight exercising. And moderate levels of exercise can be effective in helping people prevent weight gain, or for that matter, weight regain after a diet.

James Hill:
All right. So there's a lot in that, Holly. I'm going to stress some of these and maybe push back a little bit. Dan, when you go for a run, you're exercising your muscles, but you're also exercising your metabolism. And I think that's when you don't exercise your metabolism is when you get to be insulin resistant. As you said, you develop diabetes, you aren't taking fat in and out of fat cells. So we think a big part of why exercise is important, yeah, burning calories is something, but exercising your metabolism. And we're interested in metabolic flexibility. This term is still one that's not totally definitive, but the concept is if you're metabolically flexible, your metabolism is a little bit more adaptable to changes in your diet so that over time you may burn a little bit more energy than you store.

Daniel Lieberman:
Sure. Yeah. I think we agree, actually.

James Hill:
No, I agree with most of what you said. The thing I disagree on is I think it takes a lot more to keep weight off. In the National Weight Control Registry, the average exercise is an hour a day. That's the average. Less than 9% do it with no exercise. So anything's possible. But the majority do it with a lot of exercise. So I'm not sure that it takes less to keep it off.

James Hill:
I think it takes a lot to lose it, but I think it takes a lot to keep it off as well. And finally, let me tell you one study if you haven't seen this, this is a study that was published, I think, in the 1980s. The Singapore army used to let people out if they were overweight. And then they decided they weren't going to do that. They were going to bring them in and essentially put them in boot camp where they exercise like five hours a day. These people were like losing weight like crazy, eating like 4,000 calories. So the idea is you can do it, but not many people are going to do that. So we're big believers, and in this day and era, it's hard for people to lose weight with exercise alone. It may help a little bit, but you got to do a lot, but you have to do a lot to keep weight off too. And I think it's more than just a few minutes a day.

Daniel Lieberman:
Yeah, no, I mean, I mean, look, it's the dose is a complicated thing because dose involves frequency, intensity, and duration. And very few studies actually measure all three, right? So, when we talk about minutes per day, we're actually not, you know, is it minutes of running or minutes of walking, right? It's complicated. And the metabolic effects, of course, are different. And, you know, resistance training has metabolic effects as does whatever. So we have to be really careful about treating exercise like a kind of medicine.

James Hill:
I agree.

Daniel Lieberman:
Exercise isn't actually medicine. It's medicinal in a way. But it's not like you take two pills and bam, you're done, right? And what the dose is for one person is gonna be different from the dose for another person because of, as you say, there's a lot of metabolic flexibility. We all know people who just, they just look at a cracker and they gain weight, whereas there are other people who can eat as many as they want. And obviously, so there's no one size fits all. There's a lot of human variation and that variation extends to prescriptions for dose. But people, I'm sure you get the same question, but people ask me all the time, you know, what's more important, diet or exercise? And my answer is inevitably the same, which is like, it's a bad question. They're both important, right? And, you know, why is it on earth? Why do we talk? Why is that or in there? I mean, I think everybody should be, you know, be careful about their diet. And there's, I can think of very few exceptions of when you shouldn't also supplement that with physical activity, because not only is it going to help you in every other aspect of your life, your mental health, et cetera, but also it will help with the weight gain or the weight regain or the weight loss, depending upon whatever that issue happens to be. So I think we just need to be appreciative of the complexity of all of this.

James Hill:
When people ask that question about diet or exercise, I ask them, which is more important for your net worth, your income or your spending?

Daniel Lieberman:
Exactly. But it's a question I get all the time.

James Hill:
It's a stupid question.

Holly Wyatt:
It goes along with people wanting a simple answer, one thing that's going to solve the problem when there's multiple problems and there's multiple ways, things we need to do. And I think why we tend to go for a single volume, like the message is, you know, one hour of moderate intensity activity. And you're right. It's different dosages for different people. But people don't want to exercise. So you don't want to say, oh, you need to do this intensity. You want to try to make it as simple as possible because of what you're talking about with this effectiveness piece. So can we kind of talk about why is exercise so hard? Why do we push back? And really more importantly, what can we do about it? We're not out there hunting for our food.

Daniel Lieberman:
Great question. So look, I think there's two reasons and two reasons only we evolved to be physically active, right, which includes exercise. When it was necessary or when it's rewarding.

Daniel Lieberman:
And so people, you know, we play, we play sports, we have, we dance, you know, every culture has dancing, although we seem to dance less than most other cultures. So those are kinds of physical activity. Who considers dancing a form of exercise? I mean, it is, right? But we don't think of it that way. Or, you know, of course we think of sports as exercise, but the problem is that we now have a world in which exercise is no longer necessary, as we were talking earlier. And so it's counter-instinctive. And then the forms of exercise we often encourage people to do aren't rewarding. I mean, I have a treadmill in my basement and I use it sometimes, but let's be honest, it's a torture machine. It's a machine that was actually invented, the modern treadmill was invented in British prisons in order to prevent prisoners from actually enjoying themselves when they were in a debtor's prison and stuff like that. Because think about it, it's a noisy, loud, nasty machine that makes you work really hard, you get nowhere, right? And you can fall off of it, et cetera. And you're often in a dark room or in a gym with other sweaty people around you, et cetera. You try to make it tolerable by watching a video or maybe listening to a podcast like this, et cetera. But let's be honest, few people actually enjoy a treadmill for its own sake, right? Or lifting weights. So we often prescribe forms of exercise that are intrinsically unenjoyable or unrewarding.

Daniel Lieberman:
And so I think that if we're going to try to solve this problem, we have to, A, now we can't force people to exercise. Well, we force children to exercise. We have, you know, physical education in schools, though we don't do it as well as we should. But we can't force adults to exercise. We have to help them find ways to make it necessary for themselves.

Daniel Lieberman:
And we should work with people, because everybody's different, to find ways that they can make it enjoyable and rewarding. So for me, for example, one of the ways I make exercise necessary is that I'm no different from anybody else, right? One of the reasons is that because I study this stuff, if I don't do it, I'm a hypocrite. So that's an incentive. But also like on Thursdays for example I run with my colleague Jenny. I have to be out there at seven o'clock in the morning on Thursdays come rain or shine no matter what the temperature is etc and if I'm not out there she'll be pissed off at me etc. So I come up with sort of you know ways to kind of get me out the door and I'm always glad that I did it afterwards or I sign up for races and that means I have to train, you know, techniques I have to get me to make it necessary for myself. There are other people who do commitment contracts. They find a referee like my wife and one of her best friends, they actually email each other every day and they say, hey, did you do your weights today or whatever. They come up with a plan for the week and then they keep each other honest, right? And my wife doesn't want to disappoint her friends. So that works for her. But we all need ways to do it. And then, of course, if it ain't fun, you're going to be less likely to do it. So we have to help people find ways to make it enjoyable. And some people might survive on a treadmill, but most of us aren't going to really thrive on a treadmill. And so we have to find other ways.

James Hill:
We couldn't agree with you more. If you're not enjoying it, you're not going to do it. And all the exercise interventions show that we're very good at increasing exercise in the short run. But in the long run, if people don't enjoy it, they don't do it.

Daniel Lieberman:
Yep. Or there's nobody supervising them. I was involved in a study in Denmark, for example, called the U-Turn study, which you may know this study. And a great study. Oh, my God, it was so effective. We got people off their diabetes and educations. They did fantastic results. When the study ended, they no longer had a trainer. People went back to their original lifestyles because, slowly, slowly life intercedes and you got a job and you got kids and you got this and you got that and all those other things. That's what happens. Again, we have to recognize that. So we have this term in my field called weird. Weird is Western, educated, industrialized, rich, and democratic. Weird. We are weird, right? We are about 10% of the world, but this is not how we evolved and this is not how most people on the planet are. And we have to recognize that exercise is a weird thing, and it's not normal or natural, and it's an instinct to avoid it. Like when I get to my building, my office is on the fifth floor of this lovely old building. Every single day I walk to the building, and I have this little battle in my head about taking the elevator versus the stairs. And I always, I guarantee you, I always want to take the elevator, but I take the stairs because I don't want anybody to see me on the elevator. Or I remind myself just how important it is for me to take the stairs, but it's an instinct for me to take that elevator.

Holly Wyatt:
And this is good. We're wired to rest. I think that that's a message for our listeners. That's normal. Don't beat yourself up. That's evolution. That's normal. But if you recognize that, if you're aware of that and you know the positives of physical activity, exercise, moving more, whatever we want to call it, then you can start being very strategic about it and thinking, okay, how do I motivate myself? I love to be with people. So let me figure out how to insert people into physical activity for me. Or I really like to do something with my family. How do I come up with a family event? Because I'm going to need to purposely put it in because it's not going to naturally come in. And that's not a bad, that's not me. I'm not a bad person because of that. That's normal.

Daniel Lieberman:
Absolutely correct. And you have to, and physicians need to recognize this too. I mean, I'm sure you've seen the data, but only about a third of physicians, even ask their patients how much exercise they're getting or if they're exercising. And then when they do recommend it, and there's, of course, all kinds of reasons, and I'm not criticizing physicians because, you know, there's lack of sources. But there's all kinds of reasons, right? It's complicated, right? There are other reasons Are there more pressing issues to deal with, et cetera, et cetera, et cetera, you know, you only have 10 minutes to speak to your patient. There's a million reasons. But even if you do get to the point of saying, “Oh, well, you know, you should exercise.” We need to have the humility to recognize that just simply telling people to exercise is not enough. You have to come up with a personalized plan. You have to take the time to talk to them. What are the barriers? What are their issues? Do they have phobias? Is their knee hurt? Do they live in an environment where there's no sidewalks? There's so many different... Are they old? Are they young? What are the issues?

Daniel Lieberman:
And for somebody who has overweight or obesity, it's even harder. And so we have to help them recognize that. And then we sell exercise as this magic bullet. That's another term I just can't stand, is calling exercise a magic bullet. It's not. You can exercise and still get cancer and diabetes and all these other sorts of things. It's not a magic bullet. And we have this idea that if you exercise, all of a sudden, everything will be fine. You'll no longer have anxiety or depression or this or that or the other. It doesn't work that way. Yes, it reduces your vulnerability to disease. Yes, it has lots of benefits. But... It takes time. It's not perfect, and it's not a panacea.

Daniel Lieberman:
And so I think we oversell it sometimes. And then people, they try exercising, and they get on the treadmill, and it's miserable, and they don't enjoy themselves very much, and they don't lose very much weight. And they think like, “Well, this is ridiculous. I'm going to do something else.” And so we need to be very honest with people about just the complexities.

James Hill:
I agree. Totally. Holly, we're clearly not going to get through this, so we're going to have to have Dan back. But I want to turn to one other issue and get your thoughts on this, Dan. In the obesity world now, everything is GLP-1 meds. What's your thought about how physical activity plays a role, doesn't play a role in people on these medications that greatly reduce their food and take.

Daniel Lieberman:
Yeah, so I've actually just, we had a paper just accepted to JAMA on this topic. So, Gemma, the Journal of the American Medical Association. So, GLP-1s are obviously having an incredible effect for a lot of folks. But one of the concerns, and there are a number, so there are two concerns. The first is that a lot of people quit GLP-1s.

James Hill:
Most people.

Daniel Lieberman:
Over 60% from the last data box paper I read, which is a lot of people, right?

James Hill:
Yeah.

Daniel Lieberman:
And in addition, when people are on GLP-1s, and there's, of course, a lot of variation in weight loss, people not it plateaus after about 50 to 70 weeks so that's only so they're going to lose only so much weight which is still good, you know, but it plateaus and they're not going to lose any more than that. But also the evidence is that they're it's a bit like bariatric surgery. They tend to lose a lot of muscle mass a relatively large percentage of muscle mass and the scary thing about that is that as they age they're more prone to what's called sarcopenia or old age frailty and that is a huge and seriously important issue as people age. It really because it comes a vicious circle and so the way to counteract that you can try to give people more other medications try to increase their muscle mass but that's not the right way to do it. The way to counteract that is to have exercise as an adjuvant right as an accompaniment to using a GLP-1. It'll help you a lose more weight than you otherwise would on the GLP-1, I mean, not a huge amount, but more. It'll help you prevent weight gain afterwards if you've terminated using the medicine. And importantly, it'll help you maintain your muscle mass because imagine the worst case scenario is you lose a lot of weight, including a lot of muscle.

Daniel Lieberman:
You stop taking the GLP-1, you gain the weight back, but you're not going to gain the muscle back. You're going to gain back fat. And you do this repeatedly, you get this kind of yo-yo dieting and you end up with progressively less and less muscle relative to body fat. And that can really spell trouble. So I think that as the GLP-1 train continues to roll out across the world, we need to be not less, but more tuned to the importance of combining use of these medications with exercise.

James Hill:
Yeah. And one of the things that I'm concerned about, I hear people saying, “Well, when these people go on the GLP-1 meds, they're going to want to eat healthier. They're going to go to the gyms.” At least in Alabama, the gyms haven't been flooded with people on GLP-1 medications. I think there are plenty of people that are happy to take their injection, keep their weight down, and not worry about their physical activity. And I think in the long term, for weight loss maintenance, either with or without the medication, you're hurting yourself if you're sedentary and not adding any physical activity.

Daniel Lieberman:
Absolutely. And furthermore, there's another issue. So in my first book, The Story of the Human Body, I came up with this term called disevolution, which is when we treat the symptoms of a mismatched disease, but not its causes. And that keeps a positive feedback loop going. And so what's going on is that we've now got this extraordinary medication, but it doesn't prevent people from having obesity in the first place. So we don't want to lose our sight that there are other fundamental issues. Exercise being one of them, but also a healthy diet, and we should be focusing on, relentlessly on trying to help prevent people from having to use these drugs in the first place.

James Hill:
Exactly.

Daniel Lieberman:
Otherwise, we're just, you know, I'm just going to make a lot of money for the drug companies. This is not the way to deal with the problem. Which doesn't mean that somebody shouldn't use a GLP-1, but it means as a society, as a culture, as a nation, we shouldn't lose sight of the first goal, which is to prevent people from getting, overweight or having obesity in the first place. And GLP-1s do nothing to that. And they also don't help you figure out what you're going to eat. And that's another issue.

James Hill:
And from a bigger picture viewpoint, I worry that the effectiveness of the drugs for weight loss is going to lessen the motivation for actually doing the things that will prevent, such as changing the environment.

Daniel Lieberman:
Exactly. Yeah, we're saying the same thing. Exactly.

James Hill:
All right, Holly, we better do a couple of listener questions.

Holly Wyatt:
We do, but I've got my personal question. I've been waiting. I've been waiting. This is a big one for me because he's a runner. I can tell he's a runner. I'm a runner. And as I get older, I'm still running. As I'm getting older, I'm actually winning races, not because I'm getting faster.

James Hill:
You're outliving the competition.

Holly Wyatt:
I am. Just because I'm getting older and it puts me in a new bracket. And all of a sudden, they're like, call my name out.

Daniel Lieberman:
And that's the best thing about getting older. Isn't it?

Holly Wyatt:
Yeah. I win the races and people like, how many people are in your group? I'm like, don't ask. We don't need to know. The fact is I was first or, you know, but, but this whole idea people tell me and I do kind of worry, like, am I going to hurt my knees? So I know you've talked about this. What does the science say? How do you feel about, your knees and running?

Daniel Lieberman:
Again, it's complicated, right? So knee injuries are the number one injuries that runners get. No question about it. The knee is a vulnerable joint. So running can cause knee problems. People aren't crazy when they say that. However, one important caveat, running does not cause arthritis in the knee. And we have, I would say, I think at least 15, if not more, prospective gold standard studies which show that running, if anything, has a slight protective effect against arthritis in the knee. Because running, like other forms of physical activity, actually causes rejuvenation of the cartilage in the joints, etc. And we actually know the mechanisms. So, if a doctor says running is going to give you arthritis in your knee, you should correct your physician.

Daniel Lieberman:
But I think that people do get knee injuries. And my hypothesis about this, and this is the reason why I started studying barefoot running is not that I think people should throw away their shoes, but rather people who run barefoot run differently than people who run in cushioned shoes. And when you run with what's called a midfoot or a forefoot strike, and if you do it properly, and running form is complicated, there's no trade-off. You end up putting more torque, more angular force around your ankle, but less around your knee. And also, it's not just the amount, but it's also the rate at which you put it, because the rate at which you apply a force this is important for tissues. And so I think that a lot of the running injuries that people get are because they're landing hard on extended knees. They're heel striking hard.

Daniel Lieberman:
And they're relying on the cushioning in their shoe, which doesn't actually reduce the force. It just slows the rate of loading in the force. And in fact, there's a little bit of, if I can get into the complexity, when you hit the ground, right? You exchange mass with the ground, right? You have a collision. That collision occurs over a period of time. And that collision is the velocity times the mass. It's momentum, right? Velocity times mass. And it's over the time period at which your body comes to a dead stop. And when you're wearing a cushioned shoe, you still have the same velocity, you still have the same mass, but you lengthen the amount of time your foot comes to a stop, which means that the area under the curve, the impulse, the total amount of energy you deliver to your knee, because it shoots up your body like that, is much higher. So we think that one of the reasons that people are getting a lot of knee injuries is how they run. And so I think that, again, the best thing to do is prevent something before it happen. So if people are having trouble with their knees, they should take a look at their gait and see if they can run more lightly more gently maybe increase their stride rate. A lot of people run with overly slow stride rates so it's kind of complicated but good running form I think is the solution. So you can't solve all these problems with your shoes.

Daniel Lieberman:
Instead how you use your body really matters so that's why I study barefoot running because I think we can learn a lot about how our bodies evolve to run from studying the way we evolve to run which is before fancy schmancy shoes were invented.

James Hill:
So, Holly, I want to do one listener question and then I'm going to let you do your favor, which is the rapid fire questions. Here's a listener question. Is there a certain type of movement, walking strength training intervals, that is most aligned with how humans evolved? And does that make it better for weight management?

Daniel Lieberman:
The answer is we evolved to do everything. There is no one form of movement. I mean, I would say that, you know, we evolved mostly to walk. I mean, you know, that's the standard. Average hunter-gatherers walk five to ten miles a day. That's walking from L.A. to Washington, D.C. every year, right? So walking is the most fundamental form of physical activity, but we also evolved to carry things, to climb, to dig, to do occasionally, to sprint, so do high intensity. So we evolved to mix it up. And I think that's kind of what the data show, that the best exercise routines involve a bedrock of some kind of aerobic physical activity, But, you know, a little intensity is good every once in a while. A little strength training is very important, especially as we age. So mix it up. We evolved to mix it up.

Holly Wyatt:
Variety.

James Hill:
That's one of our messages, variety. Don't do the same thing all the time. Mix it up.

Daniel Lieberman:
And that's what we evolved to do.

Holly Wyatt:
It's true with food. It's almost true with anything, right? Variety is usually a good way to go.

James Hill:
All right, Holly, rapid fire.

Holly Wyatt:
All right. So these are questions that you can just answer off the top of your head. No pressure. Just fun. just like the exercise, right? Just fun. What's the number one myth about exercise you'd most love to put to bed?

Daniel Lieberman:
Oh, that it's normal to exercise. That's easy.

Holly Wyatt:
Love it. What's the most overrated piece of exercise advice you keep hearing?

Daniel Lieberman:
Oh, that's also easy. No pain, no gain. I can't stand it. Get rid of that one.

Holly Wyatt:
Okay. What modern fitness trend would you send back to the Stone Age?

Daniel Lieberman:
Oh, gosh, I have no idea. Maybe, I mean, look, I think whatever, if whatever is your, makes you happy, that's fine. I think the ones that the fitness trends that, like I just saw an article yesterday about like standing on vibrating pads.

Holly Wyatt:
That's what I was thinking. That's exactly what I was thinking.

Daniel Lieberman:
So I think it would be the fitness trend of so-called devices that actually mimic exercise but aren't exercise. Let's get rid of those.

Holly Wyatt:
Yeah. Let's see. What's the evolutionary insight most people find surprising?

Daniel Lieberman:
Oh, I think, again, that we evolved to exercise. We didn't. We evolved to avoid unnecessary, unrewarding physical activity.

Holly Wyatt:
All right. Here's a little creative one for you. If evolution designed a gym, which I don't think it would, but let's say it did, what would be the first piece of equipment it would put in it?

Daniel Lieberman:
Gosh. I mean I would think… I hate to say this but it would probably be the treadmill.

Holly Wyatt:
Yeah I like the treadmill, believe it or not. I can get on a treadmill and zone out. So I’ve learned it. Alright, last one. What's one science fact about exercise that instantly motivates people when they hear it?

Daniel Lieberman:
I think the most direct motivation is that exercise has very short-term, almost immediate effects on your mood. You may not lose weight fast. You may not prevent diabetes tomorrow. But most people feel better after they do any form of exercise. I've never enjoyed the first mile of any run. And there are times when I've gone out to do any kind of exercise and I often grumble and complain about it. But I'm usually glad that I did it afterwards. and the rest of my day goes better.

Holly Wyatt:
Yeah, sometimes I call it the 10-minute rule too. Just get out there for 10 minutes moving and usually I start to feel better at that point if you can just convince yourself to try it for 10 minutes.

James Hill:
Okay, the last segment is what we call the vulnerability segment where we try to ask you some personal questions. I'll go first, Holly.

Holly Wyatt:
All right.

James Hill:
What's one misconception people have about you as the exercise scientist?

Daniel Lieberman:
That I'm actually good. I'm a mediocre runner. I'm not an athlete. I'm an average everyday guy who has just as much trouble as everybody else to be fit.

James Hill:
Love it.

Holly Wyatt:
Okay. My question: has there ever been a moment where your science didn't line up with your life or your lived experience? And how did you or did you reconcile the two? So you're telling people one thing and you kind of look at your life and you go, okay the science says this I'm telling people this but my life isn't aligning.

Daniel Lieberman:
Hmmm. I don't know. I like to try everything I study. Yeah, me too. That's why, you know, for a while I did a lot of barefoot running because I was studying it and I thought I should try it myself. I would say that that's actually kind of interesting because I, you know, for years I really did a lot of barefoot running. I don't really run barefoot much anymore, not because I didn't enjoy it. It's just I also like shoes, too. So people expect me to be barefoot all the time, and I hate to disappoint you, but I'm not.

James Hill:
Okay, Holly, we've learned a lot from an evolutionary standpoint. We talked about that humans have been physically active, but not because it's voluntary, because they had to to get food, shelter, etc. And in the modern world, it's a whole different ballgame. Because again, if you're motivated to rest, that's perfectly appropriate. And as you said, don't shame yourself because you want to rest. And I think in the modern world, we have to be more creative about ways to help people figure out how to incorporate physical activity into their day in a way that they enjoy, because if they don't enjoy it, they're not going to do it. Dan, thank you so much for joining us this has been really enlightening and we'll see you all next time on Weight Loss And.

Holly Wyatt:
Bye everybody.

James Hill:
And that's a wrap for today's episode of Weight Loss And. We hope you enjoy diving into the world of weight loss with us.

Holly Wyatt:
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James Hill:
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Holly Wyatt:
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