--:-- Sean Rameswaram: Welcome to Today Explained, I'm Sean Rameswaram.
--:-- Julia Belluz: And I'm Julia Belluz, health reporter at Vox.
--:-- Sean Rameswaram: I want to take you somewhere today. I'm in.
--:-- Julia Belluz: I spend too much time in the studio. Well, it's kind of a studio too. It's like an 11 by 11 foot space. But fewer than 100 people every year enter these rooms at the National Institutes of Health. And this year, I was one of them.
--:-- Sean Rameswaram: Wow. And it's used to unlock one of the greatest mysteries of the human body. Which one?
--:-- Julia Belluz: The metabolism. The metabolism is something we talk about all the time, but don't really understand, is my guess. Some of you think your metabolism feels like this. A slow drip, with ripples of excess fat slowly accumulating around your waist and everywhere else.
--:-- Sean Rameswaram: Yeah, there's a big gap between how we talk about it and how scientists talk about it. So we talk about it like it's this thing that you can control with supplements. Dry caraway seeds. Chili peppers or dark chocolate or whatever.
--:-- Julia Belluz: There are things that we can actually do to boost your metabolism. You hear it on Dr. Oz all the time. On the next Dr. Oz, the nine best metabolism boosters. Turbocharge your body to burn calories faster.
--:-- Sean Rameswaram: And then the way scientists think about it, it's thousands of chemical reactions that are happening in our body at every second to keep us alive. And they turn the energy that we get from the food we eat and the stuff we drink into fuel for ourselves.
--:-- Julia Belluz: So you travel up to Maryland to the National Institutes of Health, and you let them lock you in a sealed room and throw away the key for like 24 hours?
--:-- Sean Rameswaram: Yeah. So I was basically a self-imposed prisoner of NIH. Wild. Tell me more about this chamber of secrets you entered.
--:-- Julia Belluz: I was sealed inside this chamber for 23 hours. There was a camera in the ceiling watching everything I did. Nurses were monitoring me through this little window on one of the walls of the chamber. And all I had was an exercise bike, a bed, a toilet, and that's it.
--:-- Sean Rameswaram: So on one wall of the room, there's a plexiglass window. And within that plexiglass window, there's these portals where you can pass specimens or trays in and out. And through this airlock chamber, I got three meals.
--:-- Julia Belluz: You have prescribed periods of rest where you're not supposed to be doing anything at all.
--:-- [Sound of a nurse speaking in the background]
--:-- Julia Belluz: Hope and a nurse is here. Hello. Pardon?
--:-- Nurse: I'm resting, yeah. I can't hear, sorry.
--:-- Julia Belluz: Oh, I was told to lay down with the rest periods. And the purpose of that is to see what's happening in your body while you're resting.
--:-- Sean Rameswaram: Did you hit that exercise bike while you were in there?
--:-- Julia Belluz: I did. I did about 90 minutes on the bike. Wow. Just to see what my energy burn looks like when I'm active, when I'm intentionally trying to burn off extra calories.
--:-- Sean Rameswaram: And yeah, this little exercise bag. It looks like something that was left in my grandparents' basement from like the 70s.
--:-- Julia Belluz: So what do they feed you in this metabolic chamber?
--:-- Sean Rameswaram: Lunch just arrived through these little plastic chamber doors.
--:-- Julia Belluz: Lunch is a tuna salad sandwich, a small salad, some potato chips, and a little four ounce container of cranberry juice. And I'm on what's called a metabolic diet, so it's not a diet for weight loss. It is a diet that's very carefully calibrated to maintain my body size, so based on my height and weight.
--:-- Sean Rameswaram: The kind of interesting thing about that is that they're measuring every calorie that you're eating. So the food comes in these little packages, kind of wrapped up with labels on them that are measured to the gram.
--:-- Julia Belluz: You pass the food back through the airlock portal, and they measure every gram that's left to figure out exactly how much you ate while you were in the chamber.
--:-- Sean Rameswaram: And what so interesting is that there when we talk about burning calories we talk a lot about you know we going to go to the gym and the extra spinning class we going to do
--:-- Julia Belluz: But what the chambers revealed is that the basal metabolic rate accounts for the vast majority of the calories we burn. So 65% to 80% of the calories you burn are just from you being you, doing nothing, just living and existing.
--:-- Sean Rameswaram: That's 65% to 80%. Great. So what I'm taking away here is that I just don't have to do anything.
--:-- Julia Belluz: You can just sleep all day. Just don't leave the studio.
--:-- Sean Rameswaram: One funny way to think about it is there's this amazing research where they compare hunter-gatherer societies to Western, more sedentary societies.
--:-- Julia Belluz: Okay. And there's this big difference in physical activity levels. And they find that our energy burn actually looks the same. So the Hadza in Tanzania look a lot like an office worker in Paris or in Washington, D.C. when it comes to energy burn.
--:-- Sean Rameswaram: So interesting. And why are they skinnier? They eat fewer calories.
--:-- Julia Belluz: Why does all of this stuff have to happen while you're in a metabolic chamber? Why can't you just do it, you know, as you go about your day?
--:-- Sean Rameswaram: What's happening in this room that's special?
--:-- Julia Belluz: So to understand why it's special, we need to talk a little bit about how metabolism works. So the way your body is breaking down energy, which are calories, for fuel to keep your cells going, to keep the cells that make up your organs going, to keep your brain going. That's what we're talking about.
--:-- Sean Rameswaram: So to break down calories, we need oxygen, and then we let off CO2 in that process. So it's this gas exchange. And it looks different depending on how fast your metabolism is working and the kinds of foods you're eating.
--:-- Julia Belluz: And so the metabolic chamber is just this airtight room that's able to measure this gas exchange.
--:-- Sean Rameswaram: So why did you do this? Was it just for the science? Was it just so you could write an article? Was there more?
--:-- Julia Belluz: I did it for two reasons, professional and personal. So when you're reporting on obesity and diabetes a lot, as I am here, researchers always talk about something I'm going to call the mouse mystery, which is this question of why when they put mice in cages for studies and they feed them this smorgasbord of junk food, only some of the mice overeat and puff out into these little rodent blimps, and others don't, and researchers don't understand why that happens and why even mice that eat the same amount of calories have different responses in their bodies.
--:-- Sean Rameswaram: And when you think about it, the same thing happens in humans. There's a lot of individual variation in how we respond to calories.
--:-- Julia Belluz: So an easy way to think about this is, you know, you hear it on Dr. Oz all the time. If you get a group of friends or family together, we've all been through this, and everyone has just one donut, right? Guess what happens? Everyone uses the energy differently, which is why you're so angry at your friends who are not putting on the weight that you put on when you have a donut.
--:-- Sean Rameswaram: So which donut best describes your metabolism?
--:-- Julia Belluz: So this variation is one of the greatest mysteries in modern medicine. Are you A, like Tracy? You burn it off almost immediately. Or are you like Linda, who's B? You store half? You burn the other half. You sort of right in the middle. Or are you C, like Sue? You store every, every ounce of that donut directly into your fat cells, or it certainly seems like that.
--:-- Sean Rameswaram: And it's something that obesity researchers are trying to unravel. And when they're talking about unraveling it, they talk a lot about the metabolic chamber because it's one of the most precise tools to really understand that variation.
--:-- Julia Belluz: And then the other reason I enrolled in this study, I guess, was a selfish motivation. I've struggled with my weight and struggled in the past to lose weight. When I was a child, I noticed my brothers seemed to be able to eat whatever they want and I couldn't. And the same thing with my husband now. He can kind of gulp down mounds of pasta and not gain weight, and the same isn't true for me.
--:-- Sean Rameswaram: And what did you find out once you got out of the chamber?
--:-- Julia Belluz: I found out that I'm perfectly normal. Aw. Congratulations. Yeah. My metabolism was of the speed they predict for someone my age, height, and gender. And not only was my metabolism normal but I also had what the nurses and doctors kept referring to as excellent biomarkers. Sweet. So yeah, so a healthy heart rate, good blood levels, blood pressure, and I have to say I was quite surprised.
--:-- Sean Rameswaram: Does that change like the way you think about who you are?
--:-- Julia Belluz: It made me think a lot about where we get these narratives about our bodies narratives of slow metabolism, fast metabolism, our deficiencies, our imperfections, and why I felt this inadequacy in this area when I was actually quite healthy.
--:-- Sean Rameswaram: It also made me think about how many of us might be blaming our metabolisms when that might be distracting us from what might actually be the real cause of our weight struggles.
--:-- Julia Belluz: Up next on Today Explained, all of the secrets of the metabolic chamber.
--:-- Sean Rameswaram: Julia, I read in your piece that this chamber costs taxpayers millions and millions of dollars a year. Why are we spending all of this money to send you and a few other golden ticket winners to Maryland?
--:-- Julia Belluz: Understanding metabolism is really important for understanding weight problems like obesity and diabetes, which affect up to a third of humanity right now. And we're all in this environment with lots of highly palatable, very cheap calories. Orbeez, we have the meat. But not everyone is overeating and gaining weight. And in this unit at NIH in the chambers, that's what they're trying to unravel.
--:-- Sean Rameswaram: So why is there this variation in responses to similar environments, to the calories we're given?
--:-- Julia Belluz: The other thing they're trying to figure out is why do some people who become overweight and obese develop diseases like diabetes and cardiovascular disease while other people don't?
--:-- Sean Rameswaram: So for example, they're running a study right now where they're enrolling South Asian men.
--:-- Julia Belluz: Because South Asian men are at a much higher risk of diabetes. Ah, shit. I know, sorry. Bad news. Got all excited.
--:-- Sean Rameswaram: But they're trying to understand why is that? Like, why are their bodies, their metabolisms responding in a different way than other people?
--:-- Julia Belluz: And those are the kind of questions that they're using the chambers to understand.
--:-- Sean Rameswaram: So beyond learning that Julia Ballou's has good biomarkers and a perfectly normal functioning metabolism, what have they discovered at the National Institutes of Health about metabolism in general?
--:-- Julia Belluz: They've discovered some really fascinating things. In one study, they gave people a drug that essentially causes them to pee out about 360 extra calories a day. And they found that people unknowingly compensate for that calorie loss by eating more.
--:-- Sean Rameswaram: They didn't tell the people they were going to urinate out these extra calories. They didn't tell them?
--:-- Julia Belluz: No, no, no, no. They didn't tell them. And then the people compensated without knowing, which is kind of amazing, right?
--:-- Sean Rameswaram: And that's part of this, what they call metabolic adaptations that our body makes.
--:-- Julia Belluz: Fascinating. And then they've done other cool studies, like they find that when people are exposed to cold temperatures for sustained periods, we build up what's called brown fat in our bodies. And it's fat tissue whose main purpose is heat production. And we burn more calories when we have more brown fat.
--:-- Sean Rameswaram: And so in this study people were sleeping in colder temperatures, they're burning more calories and then as soon as they put them in to warmer temperatures again, the study participants lost the brown fat in their body and burned fewer calories so they were able to again show how our bodies are adapting to these different environments, our calorie burn is speeding up or slowing down in ways that we have no control over.
--:-- Julia Belluz: This is it, everyone. All those workouts, challenges, and temptations come down to this one final moment.
--:-- Sean Rameswaram: There was another remarkable study of The Biggest Loser reality TV show participants.
--:-- Julia Belluz: Rachel, when you started this competition, you weighed 260 pounds.
--:-- Sean Rameswaram: What's amazing about that TV show is that in real life, people don't usually lose dramatic amounts of weight in short periods of time. And so these researchers were really clever. They figured out that, hey, you know, that's what's going to happen on this show. Let's take some baseline measures. Let check them during the TV show and then at the end of the season to see what happens in their bodies when they go on these crash diets.
--:-- Julia Belluz: So like the National Institutes of Health actually approached the biggest loser and collaborated in some way.
--:-- Sean Rameswaram: Exactly, yeah. What they discovered, though, was really interesting. So they found that people on the show who lost these dramatic amounts of weight in a really short period of time, this crash dieting had permanently slowed their metabolic rate even six years after the show when most of the participants had regained the weight.
--:-- Julia Belluz: For a couple of years, I kept the weight off completely, but I was exercising three or four times as much as a normal person. And once that stopped, the weight started creeping back on.
--:-- Sean Rameswaram: And so when you hear this study, how do you process that information?
--:-- Julia Belluz: Well, a lot of the shame that is on our shoulders. I mean, when you gain weight back, even when you're in school, it's shameful. When you were in front of America, it's ten times as shameful.
--:-- Sean Rameswaram: So being on this reality TV show sort of screwed up their metabolisms long term? Seemingly permanently.
--:-- Julia Belluz: They're doing like hours of exercise every day. They're dramatically reducing their calories. And the body responded to that change and like almost went into starvation mode.
--:-- Sean Rameswaram: How applicable is that to normal people? Because normal people don't really lose or gain weight like that typically.
--:-- Julia Belluz: It's actually very applicable. So the response was definitely extreme. But researchers have found that when people diet, their metabolic rates do slow down. It's not as dramatic as what we saw with The Biggest Losers, but it isn't this simple calories in, calories out system. Our bodies are finding ways to compensate.
--:-- Sean Rameswaram: Are there any final secrets of the metabolic chamber in Maryland?
--:-- Julia Belluz: They also find that people with obesity don't have slower metabolisms than you'd expect for their size. So a slow metabolism isn't actually the cause of their weight problems.
--:-- Sean Rameswaram: And I think the chambers revealed there is no silver bullet diet that has these amazing results for everyone.
--:-- Julia Belluz: And they have looked into these magical claims about low carb and ketogenic diets that they cause people to speed up their fat loss and their calorie burn. And that just wasn't true.
--:-- Sean Rameswaram: But the reason people fall for this is because people are looking for an answer on how to lose weight. Yeah, and it's really, really hard.
--:-- Julia Belluz: And And there's so much misinformation in this space and so many people trying to profit off of certain weight loss programs or diet books or theories and seize on our insecurities.
--:-- Sean Rameswaram: So what bothers you the most when you look at the picture?
--:-- Julia Belluz: Everything. I just, I'm tired of feeling bloated all the time and tired of changing my outfit 15 times before I go somewhere. I can't even look at it.
--:-- Sean Rameswaram: So a big takeaway from the research for me is that it's not a slow metabolism that's causing our weight problems. We need to be focusing on what we eat and how much we eat.
--:-- Julia Belluz: Think about it. Our genes haven't changed much in the last hundred years. People don't have less willpower than they used to. What's changed is our physical environment and especially our food environment. We're just inundated with junk food and snack food and cheap sugary calories and they're all designed to be irresistible so it's this really hard thing to navigate for people and to stay slim.
--:-- Sean Rameswaram: I think we go wrong in the U.S. by over complicating things like suggesting you have to do some kind of extreme workout to lose weight or or go on a highly restrictive diet that it just isn't sustainable.
--:-- Julia Belluz: And I think science is pointing us to the fact that much more moderate measures over time can go a long way.
--:-- Sean Rameswaram: And when I look back at what helped me lose weight, there was never a magic bullet. It was plotting trial and error, something I still think about every day.
--:-- Julia Belluz: So finding habits and routines I could stick to and things that just help me eat less and move more.
--:-- Sean Rameswaram: And I hope my experience in the chamber can help debunk some of these metabolism myths.
--:-- Julia Belluz: Julia Blues is Vox's senior health correspondent. This is Today Explained.
