Intro. [Recording date: September 4, 2025.]
Russ Roberts: Today is September 4th, 2025, and my guest is journalist and author Julia Belluz. This is her second appearance on EconTalk. She was last here in November of 2018 talking about epidemiology, nutrition, and metabolism. She is the author, along with Kevin Hall, of Food Intelligence: The Science of How Food Both Nourishes and Harms Us, which is our topic for today. Julia, welcome back to EconTalk.
Julia Belluz: It’s a pleasure to be here. Thank you.
1:08
Russ Roberts: I want to start with the way you start the book, which is The Biggest Loser, the TV show, and your co-author Kevin Hall had unusual access to the participants and found some surprising things. And I was surprised as well. So, it’s actually a beautiful example of what we think of as feedback loops or emergent order in economics. So, tell us what happened.
Julia Belluz: Yeah. Basically, the way Kevin tells it, so he had a postdoc in his lab who was sort of underemployed. This gentleman was never going to be able to publish a paper. And so Kevin was sort of on the lookout for, ‘How can I get him many participants in a study really quickly?’ And, he had this guilty obsession with reality TV. And a friend had recommended, ‘Hey, you really should check out The Biggest Loser.’ And for those who don’t know, it was basically the extreme televised version of a Fat Camp. So, you put a bunch of people with obesity on this ranch just outside of Malibu, and you make them train and eat a small number of calories essentially, and see whoever can lose the most weight, in this allotted period of time during the season, ends up winning this cash prize of, I think it’s a quarter of a million dollars.
Yeah. There was obviously–like, the show has been criticized for fat shaming and for being–it’s almost one of these things where you’re, like, ‘Did that even happen? How is this a thing?’
But anyway, so Kevin decides to approach the producers of The Biggest Loser and the doctor who is supervising the care of people on this show and ask them, ‘Hey, could we enroll the participants in a study and see what’s happening inside their bodies while they’re doing this hardcore training and dieting?’
And, he was interested in this question of–so, first of all, we knew from fasting studies and from studies of essentially starvation that when you reduce the number of calories people are eating, they have this slowdown in their metabolic rate. So, we knew that, but we didn’t really know what happens when people with obesity and quite severe obesity have this not only reduce the number of calories they’re eating, but also start to ramp up the amount of exercise they’re doing.
And, exercise was really portrayed on the show as this kind of silver bullet. It’s the thing that’s making these people lose weight. There was a lot of emphasis on the exercise side.
Long story short, he gets access: he finds a way to do this study, even though where he was working at the time, the National Institutes of Health, at first, they didn’t want him to have anything to do with the show. But he kind of finds a workaround, and they go out to this ranch near Malibu and they start to measure just about everything you could measure on the participants in this show, including their metabolic rate. And, they did this throughout this, I think it’s Season 8 of the show. And, what they found was, at the end of Season 8, they found that the people–the expectation was with all the exercise that they’re doing and the muscle that they’re building, maybe they can stave off this slowdown we see with other people who are on weight loss, who lose weight in starvation studies, or in fasting studies. So, maybe that muscle that they build is going to mitigate that effect.
And they found that that’s not true. The people who lost the most weight had the greatest degree of metabolic slowing. So, the biggest losers were also having the more-than-expected slowdown of their metabolisms by the end of the contest.
But then, the study didn’t stop there. Six years later, they had these contestants fly back to Kevin’s lab in Bethesda, and they took all the same measurements again to see what had happened. And, then there were more surprising findings. I think they regained on average two-thirds of their body weight. And despite that, they still had this reduced metabolic rate. And then, at that point, the people who had kept off the most weight still had the greatest degree of metabolic slowing. So, at both time points, the people who were the Biggest Losers–they had the most success losing weight–had the most pronounced effect on their metabolic rate.
And so, it was sort of not at all what was expected, and it’s not at all, I think as a public, what we would have anticipated.
Sorry–the other important thing was on the show at the end of the contest, they found that the people who had lost the most weight had cut the most calories. So, it wasn’t about the amount of energy they were expending through exercise.
And, at the six-year time point, the people who kept off the most weight were the biggest exercisers. So, exercise was great for weight maintenance, but not as good for weight loss, perhaps. The weight loss part of the study, it really seemed to be the calories that were cut, which wasn’t a thing that was emphasized on the show.
6:34
Russ Roberts: As a casual observer–this is not scientific–but I belonged to a gym once. And, when you go to the gym, you know, you think it’s pretty simple. It’s easy to lose weight, eat less, exercise more. And we’ll be talking about that in some depth in the course of this conversation because your book deals with it a lot. But, the exercise-more part seems–if you go to the gym, you see a lot of not-so-thin people and you think, ‘I hope they just joined. I hope this is not the result of a year-long regimen, because they don’t–‘ The gym is not full of thin and fit people.
Before we go and dig a little deeper into The Biggest Loser, explain–I know we could spend the whole rest of the time on this–but give a brief explanation of what you mean by metabolism or metabolic rate. When you say that the people who lost a lot of weight, their metabolism slowed, what does that mean?
Julia Belluz: So, metabolism, there’s a researcher that we interviewed for the book, Charlie Brenner, and he says something like, ‘Metabolism is behind everything we are and everything we do.’ So, it’s these chemical reactions, and there are thousands, maybe–I don’t know the exact number; maybe it’s millions of them–that are happening inside our body at any time to build and rebuild us, and to power everything that–the waving of my hands, the blinking of my eyes, the beating of my heart. It’s behind everything we are and everything we do. And, it’s taking the breath–the oxygen that we’re breathing in–and combining it with the food that we eat to power these [inaudible 00:08:24], yeah, to carry out these metabolic reactions that make us and fuel us.
And so, when we talk about the metabolic rate, we’re talking about: How fast is this happening? This energy transfer–how fast is this happening?
So, if you lose weight, so the–contrary to popular wisdom, larger bodies have a higher metabolic burn than smaller bodies because the energy needs are greater. Right? And so, if you lose weight, you’d have some degree of metabolic slowing because your energy needs aren’t as great. And, when the people on The Biggest Loser had this greater-than-expected metabolic slowing, so they reduced their body size, but they had even greater–they were burning even fewer calories than you’d expect for their new body size. Yeah, I don’t know if that helped, but that would be a–
Russ Roberts: Let me try to put it in non-scientific terms. And, I want to bring out more of the feedback loop, which I think is the most interesting part to me.
If you start dieting, meaning if you start reducing your calorie intake in a consistent way–and of course, we’re not consistent to start with. Most of us don’t eat a fixed amount of calories per day. We have days where we overeat, days where we might miss a meal, and so on. But let’s say, you’re at a particular level of calorie intake and you cut your calorie intake and you start losing weight. You assume that that relationship is going to be pretty constant. But your body reacts to the fact that it’s getting less food–which stinks. You’re trying to lose weight and it says, ‘Oh, not much food coming in. Maybe it’s a bad winter. Maybe the food supply is down. I better start conserving and converting more of my food into fat.’ All of a sudden what was working as a diet is suddenly tapering off. And, I think that’s a reality.
And of course, the flip side is also true. When you start overeating, your body reacts inside. And you have no control over it. It’s a very unfortunate, frustrating thing when you first experience it, but it’s just a fact that your body is a self-regulating system–a rather remarkable, extraordinary self-regulating system.
I’d say, one of the nicest things about your book is it really captures the wonder of how extraordinary the human body is, in all of its various dimensions. You rhapsodize a little bit about fat, which is not easy, but just this whole systemic equilibrating effect is really quite remarkable.
Julia Belluz: So, yeah, when you change–I think what’s underappreciated is when you change anything about your lifestyle. Let’s say you’re sleeping less, you’re drinking more, you’re exercising more, you’re changing the number of calories and the composition of your diet, your body is reacting dynamically. It’s not, like, this static thing where we cut our calories and we lose this fixed number of weight, or fixed amount of weight. And I think this gives lie to a lot of the assumptions that people have made: Just cut the Coca-Cola from your diet, or cut out the soda, cut out the dessert; and if you do that over the period of a year, you’re going to be able to lose whatever it is, X number of pounds. But, Kevin and others have done research on this, and they find that it’s not this linear equation: that it’s dynamic, as you say.
12:18
Russ Roberts: Well, let’s take sleeping as an example, because it’s a perfect example. By a very reasonable but incorrect logic, you could say the following: Well, I burn more calories when I’m awake than when I’m asleep because there’s more going on. So, if I sleep less, I’ll lose weight. If I’m awake for 20 hours instead of 17, I’ll just burn more calories during those extra three hours of being awake, and I’ll lose weight.
And, you don’t, because your body says, ‘Oh, oh, he’s only sleeping four hours, he’s under some stress,’–and it could be related to his food supply or his access to food–‘So, I’ll just slow down inside a little bit to deal with that.’ It’s not a weight-loss technique, just to be blunt about it.
Julia Belluz: Yeah. Absolutely. And, your appetite shifts, so you might crave foods that are more heavy in carbohydrate and sugar for this quick energy burst, or whatever it is, right? So, yeah, it’s complicated what’s going on.
And I think the more that people can understand that when we make these changes, that there are these things going on inside our body that do either make it in many cases more difficult; or if we make positive changes, they can make maintaining healthy diet and a healthy body size easier.
But, one of the fascinating studies on that point that Kevin did: he gave people a diabetes medication that causes them to lose more calories through their urine. So, even though the people in the study didn’t realize they were shedding energy this way, they ended up compensating for it by eating more. And, so, it’s like this example where–they had no idea that they essentially did the equivalent of cutting out the dessert or the soda, and they over time ended up compensating for that. So, I think quite fascinating.
Russ Roberts: We talked recently with Tim Ferriss–I think it was Tim–when we talked about skipping breakfast. And, I skip breakfast. I do have a cup of coffee with cream in it, so it’s not, like, a–I’m not fasting. But in general, I skip–and for most of my life, I’ve skipped breakfast. And, you might think, ‘Well, that’s the easiest possible way to lose weight. It’s even better than cutting out the soda. I just won’t have breakfast, and that way I’ll lose all kinds of weight over time.’ And the answer is of course: ‘No, you won’t. You’ll eat more at lunch almost certainly, and dinner combined to make up for that, or even more than that.’
And then, you say to yourself–and this is why I think this is such an extraordinarily interesting and controversial subject, the subject of nutrition, weight loss, and diet, and eating, which is what your book is about–you say to yourself, ‘Well, I know that I have this tendency if I skip breakfast to eat more at lunch and dinner, so I just won’t do that.’ And that phrase, ‘So, I just won’t do that,’ turns out to be remarkably difficult, even though you know that your body’s fighting against you and you know you can control what your hand has to usually actively put things in your mouth, either directly or with a utensil, saying to yourself, ‘I just won’t respond to that. I’ll just keep those constant,’ is incredibly hard.
Julia Belluz: Yeah, it’s a tricky thing. And, it gets into this debate about how much free will do we actually have, because there is this universe of subliminal signals that are–well, for our body is sending us layers of signals about how hungry we should be, whether we need more energy, whether we need even more of specific nutrients. There’s evidence of a protein appetite, a sodium appetite. So, we have that going on. And then, the more frontier science is, the food environment is sending our body signals about what and how much we should eat. And this is somehow reaching inside of us and altering–yes, which like this. It’s reaching inside of us and altering our appetite as well. And so, yeah, there’s a hell of a lot going on, and we have this illusion of control, but I think it’s a real example. Did you ever interview on the show Robert Sapolsky?
Russ Roberts: I did.
Julia Belluz: Okay. Yeah.
Russ Roberts: And, I’m more skeptical of him than you are, but it’s thought-provoking about whether we have free will or not.
Julia Belluz: It’s thought-provoking. And, I think he does a really good job of explaining how biology is about these vulnerabilities and potentials that we have, and it’s always interacting in the context of an environment.
So, with obesity or other diet-related diseases, the way I now think about it is that it’s not that: yeah, we had this societal collapse of willpower since the 1970s when obesity rates began rising. It’s not that our genes changed so much in this time, that would explain why so many of us started to struggle with weight and get fat and develop obesity and diabetes. It’s that the food environment shifted. And we had this potential in us to be great and efficient fat storers. And now, we’re put in a food environment where the deck is stacked against most people.
When I went into the book, I really thought I was a little bit on the side of the food-movement people. Let’s say, Michael Pollan and others who talk about the need to–he talks about many things, but we just need to cook. And, actually, I shouldn’t say that because his arguments are more sophisticated. But this idea that if we all just cook–if we all return to the kitchen–we can solve a lot of our problems. And that’s true, but in interviewing, I don’t know how many people I talked to who are struggling through diet-related diseases, most do not have the luxury of going grocery shopping, going to the market, and then spending hours in the kitchen cooking. And, I know this from personal experience. I have kids, and I was trying to write this book. And, the harder I was working on this book, and the closer to the deadline, the less time I had for going to the grocery store, and meal planning, and cooking. It’s hours’ of labor a day. And so, it’s not a realistic solution for most people, right?
Russ Roberts: There’s a reason, there’s a reason that processed foods are popular. And we’ll get to the topic of processed foods, but that’s what Michael Pollan would mean by cooking more.
18:56
Russ Roberts: I think it’s an interesting question: I’m sure you know people–I know I do–who effortlessly control their weight and eat normally. And, God bless them. Tim might be one of them.
Julia Belluz: Yeah, I’m married to one of them. I’m married to someone who is, like, still baffled even after I’ve worked on this issue for so long, and he has read my work, but he’s baffled by, ‘Why do some people struggle?’ He, like, can’t understand it.
Russ Roberts: Yeah.
Julia Belluz: I think he understands more after the book, but–
Russ Roberts: Well, that’s good. I have a thought on that, too. We’ll come to it also.
But, I think the question of how much control we have over our weight–or many, many aspects of our behavior–but for many of us that food environment is decisive. We resent it. For me, when I go to a buffet where it’s all you can eat–typically, it will be at a wedding or some kind of gala, gala dinner–I have a very hard time controlling myself. Even though I know I have a hard time controlling myself. And that bothers me. And, I also know there are people who behave normal–what I would like to think of as normal, at least–who don’t find those, that food piled up, that smells so good, so tempting. But your point is that many of us do struggle with that. And, I think the lesson–this is a cliché, but I think it’s an important cliché–the lesson is that, ‘Well, you just need to try harder, realizing that it’s a bad idea to overeat.’
Instead, you should–well, first of all, when you’re invited to an event like that, you have to be hyper-aware of your challenges. At least when you have more control in your home, don’t buy things that you have trouble eating in moderation, that are not good for you. And, if you do have them, put them far away. Don’t leave them out on the counter. And, I think you talk about putting something in the basement. Raise the cost, lash yourself to the mast–as in the Ulysses example–to prevent the temptation that you know you’re going to be tempted by.
Julia Belluz: Yeah, that’s sort of how I personally manage it. I just try not to bring the stuff in the house. And the stuff that is in the house is sort of out of sight, out of the way, in a different room. It’s in a cabinet that literally has, like, almost a lock. So, there’s barriers. You have to go through a few barriers to get, whatever, the food.
No, but this question of why are you someone–have you thought about that actually? Like, why, where does your struggle come from? Because, yeah.
Russ Roberts: Well, listeners know about it because I speak about it every once in a while. And I think: Of course, like almost all human beings other than Robert Sapolsky, I think I have some free will. And, my ability to invoke that self-control is not zero. I keep kosher; and I’m pretty good at it. I haven’t had a piece of pork in a long, long time, before I became a kosher keeper. I don’t give into that temptation.
So, there are many things I do control effortlessly. And yet, there are things I struggle with. And, my ability to maintain that level of self-discipline varies over time, and it comes and goes. Obviously, it’s related to all kinds of other things–stress, anxiety–
Julia Belluz: Sleep, sleep–
Russ Roberts: tension, sleep. There are all kinds of aspects that affect our daily lives that affect our ability to be thoughtful, or to be ‘not-compulsive,’ is how I would call it. And, I don’t think anybody understands that very well.
Julia Belluz: Yeah. And, the big thing that it took me a while to grasp for this book was this idea that eating behavior is a regulated phenomenon. So, it’s like breathing, it’s like reproduction in the reproductive system. Like anything that’s happening in the body to maintain homeostasis, eating behavior is the same thing.
So, we talked earlier, that these signals from the environment that are impinging on us and shaping our behavior, there’s signals from within that are impinging on our behavior. And, when I went into this book, I had this question about why was I a person–now, it’s not a big daily struggle for me, but it was. I was the little kid who couldn’t fit into the Brownies’ uniform, like, the chubby little kid. And then, my weight fluctuated. But, it continued, basically, until my early 30s. And, I had that question of why am I someone who struggles, and why do so many people struggle?
And the first place I turned was having my metabolic rate measured, and I found out it was normal for someone my age and size. And then, while I was reporting on the book, I had a genetic test, and I found out I do have this higher risk of diabetes and obesity, the higher genetic risk.
But then, when I talked to the researchers who are studying the genetics–sorry, who are studying the genetics of obesity–they all talked about how, like Robert Sapolsky would say, ‘Genes are only creating these potentials and vulnerabilities. They’re not determining whether you’re a person who is going to develop a weight problem.’
So I took this really hard look at my food environment, which is sort of, again, where the science is now. Like, the effect-sizes of studies of food environments are just massive compared to tweaking, let’s say, the macronutrient composition of the diet.
And I realized when I was growing up, we had a house where food was plentiful. My family is Italian. There was always, like, the big long table for Sunday lunches. And my mom was cooking–I don’t even know how she kept it up, but she was cooking for us all the time. But, it was also a house filled with ultra-processed foods. So, we had the sugary breakfast cereals, Pop-Tarts, any kind of chocolate bar granola things, whatever you want to call them. They’re granola bars–health foods, but they’re basically chocolate bars. A freezer filled with ice cream, frozen cheesecake. Like, a candy cupboard. It was just a bonanza. And, I was the kid like you described: I really had a hard time stopping once I started.
And then, I went back further and thought about–sorry, I don’t know if this might be more detailed than you want, but it’s a podcast, so I guess we can get into some of the details. But I asked my mom, ‘So I have this sweet tooth,’ so what you describe around food I have around sweets. I really still find it hard to control. And I asked–my mom has a sweet tooth. And I realized, when she was being nursed–she was only nursed for a little bit, and then she was given baby formula mixed with Carnation, what is it called, Carnation–
Russ Roberts: Condensed milk.
Julia Belluz: Condensed milk. She was fed–
Russ Roberts: Delicious. It’s delicious.
Julia Belluz: Sweetened condensed milk as a little baby. So of course, she ended up developing a sweet tooth. And then, we were around sweets a lot when I was little, so I developed a sweet tooth. And, yeah.
Anyway, there’s these ways that, you know, we have this biology that maybe makes it difficult, but then we’re also in certain environments. And, that shapes these habits and preferences that make it easier or more difficult for each of us to navigate our food environments.
26:40
Russ Roberts: But I would just add, and later on I hope we’ll get to the question of policy that shapes our food landscape. But, missing from your book, I would say, mostly is the fact that your mother left those–had a candy cupboard and had all those breakfast cereals and other things that you look back on with less fondness. She had those because she loved you, and she saw how happy you were when you ate a candy bar.
Julia Belluz: That’s right.
Russ Roberts: And so, one of the challenges–ometimes I imagine a world where I won’t ever eat ice cream again, because it doesn’t seem really like a really good idea. And then, I think, ‘Why don’t I just kill myself? Because I really love ice cream, and I get a lot of pleasure from it.’ I do concede that the pleasure is fleeting in some sense. But, I think a lot of the challenges–we’re animals. We are raised by parents who have deep affection for us, and they ingrain in us many habits that are not healthy out of love.
And of course, the flip side is there’s the house with no sugar cereal, no candy, a lot of broccoli and spinach. And, those kids when they reach 18 and get out of the house, they go crazy. Yes, they don’t develop the sweet tooth, but others of them I think probably have trouble from a different reaction. So, it’s not so straightforward.
Julia Belluz: No, and it’s difficult as parents: like, I am now struggling with this with little kids, it feels like. So, I take the moderation approach with them. So, in the house, we do buy on the weekend, I don’t know, an apple cake, or I’ll bake something, or we’ll have–this morning they ate brioche from a nice bakery here in Paris. And so, they’re definitely having sweets.
But, the way it feels now, I think as a parent, and I’m curious what your experience was like, but it’s like an onslaught. It’s, like, all the time. It’s available all the time. My son takes an art class, and at the end of the class they’re giving out candy. The lunch, I have to take on his school because they give them ultra-processed snacks at the end of lunch–not very nutritious desserts, or I don’t know what it is but it feels like this onslaught.
And, as a parent you have to say no all the time. And, they don’t like that because they’d rather be eating, like, what I was eating, right? But, I actually tell them, I say, ‘When I was little, Nona–my mother, they know her as Nona–she would feed us lots of these sugary cakes. And, I really had a tough time as a kid, and I had a tough time playing sports.’ And so, I try to explain to them, ‘We’re trying to keep you healthy, we’re trying to protect your teeth. And so, I can’t say yes all the time, but you can enjoy it sometimes.’ So, they’re sometimes foods. But it’s very difficult.
Russ Roberts: Sure, of course, it is.
Julia Belluz: Really difficult.
Russ Roberts: And of course, with Italian food, you know what they say: You eat a big Italian meal, then three or four days later you’re hungry again. But, we are both from cultures that have a lot of emphasis on food. Again, I want to emphasize we’re going to talk the whole time about the fact that sometimes we want to eat less or weigh less, but food is a wonderful bonding. Just talking about food, I started salivating.
30:26
Russ Roberts: So, let’s move on. I want to move on to a significant part of the book that listeners of EconTalk will be very intrigued by–and I want you to summarize it, which is the intellectual fight between Gary Taubes and your co-author, Kevin Hall.
Gary Taubes has been on the program, I think twice. And, he became famous for arguing that a calorie is not a calorie. Some calories are worse for us than others. In particular, carbohydrates and sugar are bad for us, and they change our metabolism, they change other things in the dynamic system that you were talking about.
And, he founded, with support from the Arnold Foundation, an institute NuSI, N-U-S-I, to examine this question more seriously. His books and articles made the argument that we have misunderstood nutrition and metabolism, and we’ve emphasized calories rather than the kind of calories. And in particular, he was, again, arguing against carbohydrates and fat.
And, Kevin Hall became an antagonist of Taubes because of what he found. And then, there’s a debate about what it means. But, I know many listeners–and this is what’s fascinating–I know many listeners, because you wrote me, listened to the Taubes episodes, cut out carbs, or reduced them dramatically in sugar, and lost lots of weight and felt better, changed their life.
The challenge is: It can be the case–and, this is what’s fascinating–that cutting out other things can also help you lose weight. Which does not seem logical. On the other side. So, talk about what this debate is about, and what do you think the state of the science is? And you’re very respectful–meaning you and Kevin writing together of Taubes’s work. It’s not a diatribe. I’ve had a number of people send me books that are either diatribes on one side or the other of this issue, but I really appreciated the thoughtful and nuanced way you approached it.
Russ Roberts: So, summarize where you think the state of this debate is, and why you think we are where we are.
Julia Belluz: So, first of all, yeah, I love Gary. I love debating with Gary, and I’m sure he was a great guest on your show because he’s a great talker and debater.
So, I think that–the question that Kevin was examining was how does the body exchange these two different fuels? So, I guess the body has three fuels: protein, carbs, and fat. And, when you reduce the carbs or the fat in the diet, what happens to the composition of the body when you hold calories equal?
I think Gary argues, as you and your listeners would know, when you reduce carbs, you create this milieu in the body that leads to this fat-burning advantage, or this metabolic advantage, and makes weight loss easier, reduces hunger, has these other advantages. And, I’m not surprised that–I should say, what we try to make clear in the book–different diets can be effective for different people, for sure. Like, there is no one-size-fits-all to this.
We kind of know what a healthy diet generally looks like. So, with Kevin’s study, and even the research that Kevin and Taubes collaborated on, it was this question of: if you reduce the carbohydrates in the diet, you have this fat-burning advantage over reducing fat in the diet.
And, Kevin tests this repeatedly in several different studies and finds it’s sort of a wash. People lose about the same amount of body fat on whether they’re eating low-carb or low-fat. It ends up being a wash. So, actually there was a slight advantage to the lower-fat diet, but it was negligible. They seem to have about the same effects in Kevin’s studies.
I think what Taubes argues is that they didn’t run for long enough. So, if you make this study last, let’s say six months, you would see something different than you see at six or eight weeks.
And then, Kevin would say–he’s basing his argument on the existing evidence–and, it does seem like a calorie is just about a calorie when it comes to fat loss.
But I think what this debate has overshadowed is that these different diets do create these different hormonal–they create these different responses in the body that can have different effects on the immune system. That’s one frontier of the science. So, when you change the macronutrient composition, you have a different immune response. They can be used as treatment for different things.
So, low-carb diets–you probably got into this–have long been used, for example, to treat epilepsy. There’s all these different endpoints that are way more interesting, I think, than the fat-loss piece of it. So, that’s what I’m more interested in.
And it feels like–what we kept finding in the book for many of these issues is this feeling like it’s all been a big distraction. Like, with metabolism, we obsess over slow or fast metabolism and body weight when it’s this life-giving force in our bodies that kind of explains life itself.
Or with–what’s another example? With this low-carb versus low-fat diet. You can put people on these diets. Some people will have success with the fat loss, but I think there are so many more interesting questions to explore than that. And it seems like–I’m quite convinced that on average, so there’s always going to be a curve of people who are responding in different ways. Some will lose weight, some will gain weight. Most people will fall somewhere in between. On average, it’s a wash: When you reduce the carbs, when you reduce the fat, if you hold the calories the same on average it’s going to be a wash. But, there are all these other things that we can explore by tweaking the composition of diets. And, I find those questions a lot more interesting.
37:17
Russ Roberts: But, if the only thing we care about is weight loss–for me, there are two questions. Question Number One is: What’s your ability to maintain the regimen? So, some people are very disciplined. They either have a better internal set of skills, or they care more, or whatever it is, and they can stay on one of those diets for a long time. So, they can reduce their calories and cut out either–either–carbs or fat. And they’ll both lose weight, but they can’t stay on the regimen, is the challenge.
So, I’ve done low-carb a number of times. When you do low-carbs, you lose–and it would turn out, it might be true if I did low-fat–you lose a lot of weight, and you feel great. And then, there comes a day when there’s a plate of French fries in front of you. And, not only do you want those French fries more than anything, you put that first French fry in your mouth and your body goes crazy. It says, ‘I haven’t had one of these in about six weeks, and I really miss them.’
And, you find it extremely hard–to come back to our earlier point about willpower–you find it extremely hard not to eat a lot of them. And, I suspect your body reacts to them differently than it does if you’re eating them occasionally, now and then along the way. And so, I cannot maintain–plus, I have a social life: I’m married, my wife likes to make different food. If I said to her, ‘From now on, we’re going paleo,’ I don’t think she’d divorce me; but it would be challenging. And, I go to other people’s houses, and I don’t want to tell them I keep these certain rules, because it’s not life-threatening in the moment. So, for me, while a low-carb diet is very powerful in helping me lose weight, it’s a short-run phenomenon.
If I have to fit into a suit six weeks from now, it’s not a bad way to go. But, your point is, and what Kevin would argue, and maybe Gary would agree, even over a short period of time, I could cut out fat, too, and it would also have a good effect if I could keep my calories down.
But, what I’ve learned from all of these debates–and it’s really fun, by the way, to believe that there’s the secret thing that if you knew about it–and I think part of the challenge of your field is that there’s always a secret thing. And, people sell it, and people want it, and they’ll pay for it. But, the secret thing is simply, you can’t eat so much. If you count your calories and you keep them below, in my case, 1800 to 2000 a day, I’m going to lose weight. And, if I take in more calories than that, I’m going to gain weight. And, it doesn’t matter what kind of calories. That’s what I’ve got from this. Am I missing anything?
Julia Belluz: I think that sums it up. But, I think the important point is for every one of you, there is a Gary who can do the low-carb, loves the low-carb, adheres to the low-carb–
Russ Roberts: Fair enough–
Julia Belluz: They find it easier just to cut it all out, and they don’t have the cravings. And, they actually say, ‘Yeah, the cravings are better than ever.’ And, I’ve interviewed these people, I’ve written about these people. They exist, they’re real, and they’re some of the listeners of this show.
But I’m like you: I tried every diet, and nothing stuck. I couldn’t adhere to it over the long term. And, when I would cut things out, it would increase the cravings for me. If something was really forbidden, then I wanted it even more. So, I don’t know. But, then, yeah, there are people on the other side who have these tremendous successes.
But, what I became fascinated by–and this is where Kevin’s work shifted as well–this idea that, so you would find these marginal differences with this topic we talk so much about tweaking the macronutrient composition of the diets for fat loss. The differences were marginal to almost non-existent. But where you find massive effects is changing the food environment.
So, when Kevin would expose people to food environments that were mainly offering them ultra-processed foods, and then food environments that were–the whole food environments and telling them in both cases to eat as much or as little as they wanted. They would eat–I think in the studies it’s, like, 500 to 1000 more calories in the ultra-processed food environment spontaneously. And then, the effect sizes on calorie consumption and weight gain, they just way outstrip what these macronutrient comparisons would have. They would gain more weight, much more weight. I guess, sorry, on the other side, they were losing weight. But it has so much more of a dramatic effect than these individual diet tweaks, if that makes sense.
Russ Roberts: Yeah. But, that comes back to your point about being a mother of children, with a job, and all kinds of other complications in your life. It’s hard to live that non–it’s not hard. It’s costly to live a non-processed life. A life where you make your own food. There’s something beautiful about it. It appeals to me. I have romance about it. I’m sure you do, too. As an Italian living in Paris, it’s powerful, I’m sure. But it takes a lot of time. And, it’s actually pretty cost-effective, monetarily. But, time, it can be brutal.
And, so, we’re constantly tempted by that, just as we are tempted by its deliciousness. As you point out in the book, it’s been engineered to be delicious to my palate, which makes it hard to resist.
Julia Belluz: What we end up calling for in the book, the diets that are the most healthy for us in countries like the United States and other high-income countries are the most time/labor-intensive, the costliest, the hardest to access. And, the worst-for-us diets are the most accessible, the most affordable, the most in-our-face, omnipresent. And so, we call for this inversion of the food environment in the book. That’s what needs to happen. We need to pull every policy lever possible to invert this food environment. Yeah, as you say, most people aren’t going to have the time, the energy, and the wherewithal to do this daily battle that you have to do in a place like the States, or in many parts of the States, and in many other countries right now.
But, I’m sitting here in Paris, and what they get right here–so I said earlier, I think–I went into this book thinking it would be great if we all cooked more, and this would solve a lot of the problems. And, I very quickly realized not only do people not–they don’t have the time to cook, maybe they can’t afford the ingredients to cook. But, a lot of people don’t want to cook. They don’t have the know-how anymore. This knowledge, it’s lost in a generation. And now, it’s a couple of generations in the United States, certainly, where that’s been lost.
And so, one thing that would be great is if we had more accessible and affordable, healthy prepared foods, and some of those can be ultra-processed foods. An, so, I’m sitting here in Paris where–first of all, there’s an embrace of fast food that I think is really overlooked. Just on my street, chocolatiers, bakeries, cookie stores: like, everything you can imagine.
But, there’s also a lot of healthy prepared foods. So, one of the first words I learned when I moved here was traiteur, which is a caterer. And so, you can go into these places and you can buy a roast chicken, or potatoes, and prepared vegetables. And, they’re all over Paris, so that’s one thing.
Another thing: a very popular chain here is Picard, which is basically a store. It’s like a grocery store where it’s all freezers. I don’t know if this exists in the United States. If it did, I didn’t know it, but it’s reasonably healthy frozen food, meals–like, you can get a Thai curry or whatever it is. And, the Parisians love Picard, so this is all over Paris.
And so, there are these options that are quick. Maybe they’re not the most affordable, but they’re not prohibitive, and they’re extremely accessible. And, you can eat a reasonably healthy diet without cooking everything from scratch. And, I think that’s missing in a lot of high-income countries. And, it would be great if these meals were subsidized, if they were more accessible for people. And, we–
46:10
Russ Roberts: I’m going to push back. But, before I do, I want to quote Stendhal who, at least in my memory, is quoted as saying, when he first tasted ice cream, ‘What a pity this isn’t a sin.’ Meaning, forbidden things are even more tasty.
But on this issue of–Europe is an interesting example. I’m in Israel. Israelis eat all the time. You see them on Friday mornings, they’re–Friday is the first day of the weekend here. Saturday is the second day, Shabbat. So, on Friday in an Israeli cafe, people are eating. And they’re eating all day long, it feels like. They’re eating at two o’clock in the afternoon, they’re eating at 4:00. And at night in Tel Aviv–you can go to, a lot of places are open at midnight, and people are eating large meals. They’re not, like, having a little snack. And, there aren’t that many overweight people here when you walk around.
The same is true of Italy. I love Italy. I’ve spent a lot of time there recently. Actually, Italy is underrated, as great as it is. I think it’s even greater than people think. People in Italy, they eat all these carbs. They’re eating tons of pasta, gelato, sugar, pizza. Obviously, there are overweight people in Italy. There are overweight people in Israel. But, on average, you walk around on the streets, they’re thinner than they are in Israel, and in Italy, and in France than they are in the United States.
Now, one of the reasons for that, which is not much discussed in your book, but it’s implicit, is: the United States is a very wealthy country, on average. Yes, some poor people have challenges, and it causes them to eat food that’s not healthy for them, and fattening. But, on average, Americans are wealthier and have a higher standard of living than many Europeans. And, as a result, they can afford food. And food is cheap in the United States.
America’s–capitalism, for better or for worse, is really good at giving people what they want. So, in the restaurants, the servings are large. It doesn’t matter whether, as we’re making the point, whether it’s pasta or not. Whereas in Italy, they’re smaller. There’s a whole bunch of reasons. If you Google this on the web, you’ll find a lot of different theories. Most of them are probably wrong. But it’s a number of factors.
But, the simplest answer that economists give–and there are papers written on this–is that the reason we’ve gotten fatter is that we’re really good at producing food in restaurants and in farms. And so, it’s really inexpensive. And, when things are inexpensive, people buy more of them. And, that’s the essence of the problem.
So, what I want to challenge you, turning this inverting the food landscape, there are a lot of things that we like that aren’t good for us. Food is one of them: that we eat in non-moderate ways in the United States. And, I don’t want to get the government in the business of trying to curb my worst habits. They shouldn’t subsidize the bad things, for sure. But I’m not sure we want to subsidize good things and shame people through the government. You could shame people in your book–good for you. And, Michael Pollan can. But I don’t think we want the government in that business. The H. L. Mencken line, which I butcher, but the gist of it is, ‘Puritanism is the haunting fear that someone, somewhere, is having a good time.’ That’s America. They’re having a really good time. They’re eating a lot of sugary cereals because they’re relatively inexpensive. And they’re eating a ton of pizza, and a lot of it’s processed on top of the fact that it’s a lot of calories. Capitalism gives us what we want. Yeah, we struggle with what we want sometimes because it’s not always good for us. But, do you really want the government to decide what we should do?
Julia Belluz: Okay. So, I’m going to give you an analogy, but first on this comparison with Europe and the United States. I think one important aspect of food environments is culture, right?
Russ Roberts: Yeah.
Julia Belluz: And so, there are very strong cultural mores in France and Italy–I’m sure in Israel as well–about when you eat, how you eat, what is eating, what does it mean to sit down at a meal with your family and friends? You’re not going through a drive-through and buying a Big Mac and fries and eating it while you’re driving back to work, or whatever it is, right?
Russ Roberts: Exactly.
Julia Belluz: And, the Michael Moss Salt Sugar Fat book is a great exploration of how the food industry created American–or whatever was there–or recreated American food culture in terms of portion sizes, constantly eating, snacking. They went after women who were entering the workforce with these convenience foods and sort of pushed it on families. And not only pushed it: families wanted them, right? One of the big changes we don’t talk a lot about, but the reason we don’t cook as much as we did in the past is because women went to work. This is a massive cultural shift that changed how we eat and what we eat.
Okay. So, the food culture is so important; but what I now appreciate, especially living here, the food culture has been helped by government policy. So, for example, in France, there’s a–I need to explore this more, but my understanding is that there’s a limitation on how big the supermarkets can be, to preserve the culture of fresh food markets. And, when you think about, what do you buy at the supermarket that you can’t get at a fresh food market? It’s all the crap, right?
Russ Roberts: Yeah.
Julia Belluz: It’s all the junk. And so, there is this tradition of fresh food markets. I don’t know if all these healthy prepared foods I was talking about are subsidized in any way. I don’t know if that’s more cultural, that people just have that.
But they also love fast food here. So, that’s a conundrum.
But okay: so they have policies like that. They have policies on–certainly, like, walkability and active transportation versus car use. They have policies on feeding kids sustainable, healthy food at public school lunches. So, that’s a real thing. There are all these little levers that they pull.
Now, I think this is discontinued, but one of the reasons France had this historically low obesity rate was related to teaching people–cooking was part of school curricula.
But, yeah, we’ve talked about the cultural and social changes that have made it certainly more difficult for people to cook. But, I think all these things sort of create these environments that maybe nudge people in one direction versus another.
So, the analogy I wanted to try on you is this idea that Americans have been exposed to the equivalent of a release of a toxin from an industrial plant. And, we’re telling people: Take personal responsibility, wear continuous glucose monitors, put on a wearable–that’s going to help you with the toxin. Go get advice from your doctor on how to take personal responsibility for this toxic waste that has been imposed on you by your environment. That’s what we’re doing with the food environment. I think, actually, we need as citizens to demand that we’re protected from the kind of toxins that have become ubiquitous in our environment, in our food. I don’t think we can expect that personal responsibility is going to move the needle. It hasn’t until now.
Russ Roberts: Well, I don’t like the analogy. The conclusion I can’t disagree with, although we’ll close with something related to personal responsibility. But, I think my thought on that analogy is the following: the dose makes the poison. Meaning, most chemicals and most things that we ingest in small amounts can actually be good for us, and in large amounts can be poison, but in small amounts they’re fine.
And, we’re talking about food. So, the first thought is that it’s not a toxin; it’s actually the opposite. It’s a life-giving, life-enhancing activity, eating. And I don’t–well, I know I don’t want the government involved in it in the ways that I think maybe you and Kevin would.
But, I think the other challenge is–the reason that it’s not appealing to me–is that there’s always a temptation to assume that, well, the government will only control the really toxic parts of eating–the ultra-processed foods and the really unhealthy things, the sugary cereals and those kinds of things. Again, forgetting the fact that it can be for some people an important joy of childhood.
And, I am somewhat agnostic about interfering. Well, I’m very against interfering with it. I’m agnostic about whether it’s literally a bad thing, or not–a toxin. Although I do see its dangers.
But, let’s say it decides that those frozen things that you like are, ‘No, that’s not good either.’ And, more importantly, the groceries that aren’t being hurt economically, financially, by the frozen food folks are going to argue that the frozen things are a toxin. And so, that’s a Pandora’s box for me. I know reasonable people[?] can disagree about that, but that’s the main reason I think we shouldn’t go in that direction.
Now, what’s the alternative? Leaving it to personal responsibility, I understand, is pretty not going to do so well, so I concede that, too.
Julia Belluz: No, I think that that’s what we’ve been doing, and it’s been a miserable failure. And, it’s led to not only, like, a massive amount of public money being spent, but suffering. People are seriously sick from–yeah–now, multiple chronic diseases at once that are related to the food they’re eating. So, business as usual can continue, but I don’t think it’s a particularly wise approach. [More to come, 56:45]
