Weight Loss: Why Won't It Stick?

0:00Wow! Wow, wow. So it's real. It is true. It is true that weight cycling can mess up your metabolism. Not so fast. Hi, I'm Wendy Zukerman and this is Science Versus.

0:18Today on the show, why is it so hard to lose weight and keep it off? plus what happens to your body when you lose a bunch of weight and put it back on and lose a bunch of weight and put it back on because the internet is saying that this cycle which is very common is actually really really bad for your health but is it true and just quickly before we get started I do want to say that if this is a sensitive topic for you please take care while you're listening to the show and we're going to put some resources in our show notes okay to get into the science here, we have senior producer Rose Rimler.

0:55Hello, Rose. Hi, Wendy. Where do we begin? The first thing I want to do is I want to introduce you to someone I recently talked about this quite a bit with. His name is John Rossi. He's a musician. He's actually a drummer. I called him up because he is someone who has struggled a lot with his weight. I have been weight cycling most of my adult life, and it's not fun. Weight cycling. So this is the term for when folks lose a bunch of weight, put it back on, lose a bunch of weight, put it back on, right? This is the new internet term that I guess in the 90s we were calling yo-yo dieting. Yeah, I think so.

1:34I think weight cycling is like a little bit more, sounds a little more scientific or something. And so John's story is that he initially lost a lot of weight in his 20s. That was like the first time he ever lost weight. He lost quite a bit of weight, and his appearance really changed. People, he said, were complimenting him a lot. He was getting a lot of positive attention. And it changed a lot of things for him. He said it changed the way that he dressed. So he said that before this happened, he was wearing dark T-shirts and baggy jeans. And now I was wearing the most, like, funky pink cool stuff and skinny jeans.

2:11And I was in it to win it. What was your wackiest outfit from that time? I had, so I had a pink t-shirt that I like to wear with a pink, like, flannel over shirt, like a button down over it, unbuttoned, with matching pink sunglasses. That sounds pretty rad. It was so bright and it was so good. And I miss it. He eventually gained back a lot of the weight that he had lost. And so he put his pink outfit in the basement. So that was the first time. But he's since then gone through a bunch of these cycles. Losing weight, gaining back weight, losing weight, gaining back weight. And he's not alone. Studies find that up to half of adults in the U.S.

2:54have gone through at least one weight cycle. Half of all adults in the U.S. have experienced this. Yeah, it's very common. And it's also very common for it to happen repeatedly. So another survey found that of people who do weight cycle, they go through on average eight cycles by the time they're middle-aged. And, you know, he's right on track for that average. I am currently on my ninth time trying to lose weight. Wow. And how many pounds do you think that is over the course of your life? I mean, if I had lost all of this together, I'd be in the negatives. Yeah, you'd like lost your entire self.

3:30Yeah, yeah, yeah. Like, I have lost multiple people, you know, over this time period. In fact, he says he's lost and put on hundreds of pounds over the last couple of decades. Yeah. You know, John has worked so hard so many times that when this happens, it just feels awful for him. Terrible. Like, truly, like, I was failing myself. And I was, I was, you know, I had succeeded at something and then failed at it. which I think is probably worse than just never succeeding at something. And it's really hard. It is. I would take every other challenge in my life and double them if I could get rid of this one.

4:16Yeah, I heard similar things from other people who I spoke to for this episode. Listeners called in and just seemed like there is a really common theme of frustration, sadness, and then also a lot of self-blame. Ugh, you know, I've done it again. I just couldn't help myself or I wasn't paying attention or I wasn't doing what I was supposed to be doing. I don't know how to get out of this cycle. When I was with a bunch of friends and had to climb on a scale in front of a bunch of people to be weighed to see if I could ride a ride at a carnival and my weight was right back up to where it had been, over where it had been before I started Weight Watchers, three years before, I was devastated and went into a depression spiral that lasted for years.

5:16So people really want to know more about why this happens to them. And in this episode, we are going to get into that. Yeah. But we're going to get into more because beyond sucking, which it clearly does, now there's a lot of internet claims that say that this is actually bad for your health. Cue the influences, Rose. Yo-yo dieting is so bad for us. Not enough people are talking about how damaging repeated weight loss and regain can be. It wreaks havoc on our body's internal processes and the infrastructure that keeps us alive. Yo-yo dieting is killing you. And specifically what people talk about is that you're like ruining your metabolism.

5:58Right. That you're going to end up with higher body fat percentage and less muscle than you would have otherwise. And that you're just, you're going to be sick. You're going to get diseases like type 2 diabetes, heart disease, that kind of thing. And you would have been better off if you just never tried at all. Kind of is the implication. Yeah, some people say that. So we're going to get into all of that. We're going to do that for John too. John is a very science-y person, but he says this one, this is kind of hard for him to dig into. This one's too close to home. I've read so many things. I've heard so many things.

6:32I just want to hear from people that I trust, like a true scientific look at all of this. Because I can't. I can't at this point. I really felt like, do-do-do-do-do-do. Rose. You got your cape? You're a voice we trust. Oh, I have my cape. It's my cape, actually. Yeah, yeah, yeah, yeah. I'm just in costume. I'll be the voice. Yes. The science on weight cycling and is it really killing you? Coming up after the break.

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8:43Welcome back. Let's find out why it's so hard to lose weight and then keep it off. Because everything's political these days, it actually almost feels like the woke thing to say is it's so hard to lose weight and keep it off. And the people who say it like it is, they'll tell you, if you diet and keep that diet, you can lose weight. you know so is it is this just wokeness and unwokeness gone mad or give me some actual data here i mean if it were that easy we wouldn't have things like uh the national weight control registry which is set up to specifically find people who can lose a lot of weight and keep it off and track them and study them that's how rare it is to lose a significant amount of weight and keep it off for longer than like a year.

9:40Right. And one person I spoke with, Elena, she's an actor from New York. She had heard about this registry. That was like my goal was like, I want to be in the registry.

9:54So I guess like, you know, if people do lose a bunch of weight and keep it off long term, is there anything like why? What's special about them? Are they addicted to exercise and psychotic about what they eat? And that's the only way you can do it? Great question, Elena. What's happening? Is that what's special about them? Well, the scientists behind the registry have shared some things that these people seem to have in common. Some of them are kind of random, like they tend to eat breakfast. Oh. So take with that what you will. They also exercise a lot, on average an hour a day, these folks. An hour a day.

10:39Yeah, that's committed. Yeah, and to Elena's point, like are they, I think she said, psychotic about what they eat? I don't know if they're psychotic about it, but they're very careful. The researchers said that they exhibit, quote, a high level of dietary restraint. So it really becomes their whole life. It has to become very important. Yeah. Okay. So then why is it? Why does it take so much? Why does it take so much? That's right. Yeah. So there's a few reasons. One is that when you lose weight, your hormones change. Your hunger hormones increase and your fullness hormones decrease. So if you, to this point of if you just stayed eating a certain number of calories that allowed you to lose weight in the first place, if you just stayed on that diet forever, you could keep this weight down.

11:30Actually staying on that diet forever becomes harder and harder. Yes, it becomes harder and harder because your body is nudging you towards eating more to counteract that weight loss. and there's a really cool study I want to tell you about that shows this and shows just how like below conscious awareness this is happening. So in this study, researchers gave people a drug that pulls sugar out of your body and into your urine. So you end up peeing out a lot of sugar. This is in the diabetes world, this drug. Because you're peeing out a lot of sugar, you lose weight. You're like excreting calories.

12:08So people on this drug tend to lose weight. If you tasted your urine, it would be sweet? Yes. Okay. You know, if you run out of honey, you know, it's good to have a little backup. This was a controlled study. They also had people take a placebo pill. They had another group on a placebo pill. So if you were in the study, you didn't know if you were given a pill that was causing you to excrete more calories or not. Okay. Uh-huh. Then they followed people to see kind of like how they ate after that. And they found that the people on the drug, without knowing that they were losing weight, started to eat more.

12:47The people on the placebo drug know that it wasn't that kind of change. Right. So just like those hunger hormones kicking in, they were just a little bit more hungry. Just a little bit, yeah, but it adds up. So this is one reason why it's so hard. Your body wants to conserve calories, which for most of human history, we were hunting for food. Food was hard to get and that's how humans evolved and now it's very different. So it does make perfect sense that there are these things beyond our control in our body that are pushing us towards weight gain rather than weight loss. And I think this is why it's so confusing and frustrating for people because they're still eating below what they want to eat.

13:34They're still like restricting their dietary intake. I heard someone give a talk where they said keeping off weight is like holding a rubber band really tight. So you have to keep holding it. And it's very hard to do that. Eventually you relax a little bit. And another thing that people bring up is about metabolism. this idea that your metabolism changes from weight loss. And that's another factor. That's right. Because people, the people who say that weight cycling is dangerous, wasn't one of their arguments was that it actually breaks your metabolism in the end, right? Right. Therefore, making it even more difficult to lose weight.

14:13Yeah. So let's dive into metabolism. Yeah. I talked about this with Faden Madkos. He's a professor in the nutrition and exercise department at the University of Copenhagen. And the first thing he told me was that, yes, your metabolism will get slower when you lose weight. When people lose weight, they burn fewer calories. And this happens both at rest and during exercise. And that is completely normal because a smaller body actually needs fewer calories to sustain its function. So it is true. It is true. As you get smaller, your metabolism does slow down. Yes. So basically what our metabolism is mostly doing is running a complicated machine.

14:55The size of that machine matters. If you're a bigger machine, you need more energy. You need more calories. If you're a smaller machine, fewer calories, less energy. And so as people lose weight, they have a smaller machine to run and they need fewer calories. And that in itself could be challenging to sort of dial down your calories more and more. All right. So then can we take it one step further? Because the internet always does. Yeah. If you then weight cycle, does over time that process break that machine of ours and ultimately break your metabolism in some way? So the people who talk about this, they often talk about this one particular study.

15:35Let's talk about the biggest loser study. The biggest loser study? It's the biggest loser study. The biggest loser. Remember that, Wendy? The reality show? Yep, the reality weight loss competition. Uh-huh. Yes, of course I remember it. Yelling. Lots of yelling at people. Lots of yelling. Dan, no! I can't. Yes, you can! Get back to work. Come on! Dina, come back, Dina. You're acting pathetic. It was really intense. It had people do hours of exercise a day, like two or three hours a day, while they were cutting calories as well, significantly. It was mad. It was mad when you think about that moment in history.

16:11And then everyone would go for the weight, where they would measure themselves and everyone would line up. The public weigh-in. The public weigh-in. Yeah. It's just so medieval. It's brutal. And it was just, wow. Wow. Okay. We were doing that. Why are we talking about it on Science Versus? Because one good thing, interesting thing came out of that show. Science. We have some science from that show. Because one season, scientists actually followed contestants before and after they were on the show, measuring their resting metabolic rate. So they did that before they started the show, before they lost weight, and then after the show when they had lost weight.

16:52And they lost a lot of weight. On average, this group of people, it was like 16 people, they lost about a third of their body weight on average. Wow. And so did their metabolism slow down as expected? So it slowed down, of course, because they're smaller. Machines were smaller. But then the question is when they put the weight back on, did they? What happened next? They did. So over the course of six years, most people put some of the weight back on or all of it back on. And the scientists circled back. They got back to them after these six years and they measured their resting metabolism again.

17:33And so you would expect if the weight had come back, then the metabolism would bump up as well. Right? That's right. So what happened? They didn't find that. these folks, their metabolism on average was still suppressed years later. By how much? Well, here's Faden. So their resting metabolic rate was lower than predicted by about 500 calories per day. What is that in food? It's a Big Mac. Okay. Wow, a Big Mac a day. That's how much their metabolism had dropped on average. Right, meaning like next to someone who hadn't had this experience but was sort of the same size. Yeah. That other person could eat a whole extra meal, essentially.

18:22Yeah. Per day than they could to stay the same weight. So it's weird. It is true. It is true that weight cycling can mess up your metabolism. Not so fast. Okay. This is a weird study. It's small. What people did is quite extreme. we have other studies that are a little bit more in keeping with the reality of what happens to most people and bigger more people in the studies great yes this was just 16 people right okay so what else what are other studies show some studies do also find some some effects some like suppression of the metabolism it's not just the biggest loser okay right but the biggest loser found the biggest extreme results.

19:05Most of the studies find something much smaller. And in fact, a meta-analysis found it was quite a small amount on average. The metabolism lowered by a small amount on average. Yeah. And it's actually so small that Faden argues that it actually could be within the margin of error for what these measurements can actually detect. Uh-huh. So this is good news for John, who's been weight cycling nine times, right? It suggests he hasn't broken his metabolism, right? Yeah, yeah. And I called him, actually, and after we talked the first time, after I'd done some research, I called him back. And I told him about some of the science here, including this metabolism finding.

19:48I've been told by so many people my whole life that I, you know, that I am hurting myself and I am causing myself these, like, long-term issues. From the weight going up and down? Yeah, yeah, yeah. To the point where it has scared me to try losing weight sometimes. And I'm like, no, what if I'm doing more damage? And so that's really encouraging. Science to the rescue. Science to the rescue. We're such nerds. I know. So it's nice because science doesn't always come to your rescue, you know. It does not. And sometimes it really kicks your ass. Okay. So the next thing I want us to look into is what happens to your muscles when you lose weight and then put it back on and lose weight and put it back on?

20:36Because the way some people talk about it online, it's almost as if your muscles will disintegrate over time. Do you know what I mean? I mean, the internet is so extreme. What is happening to your muscles? It's extreme. What people do say is that, you know, when you lose weight, you lose some of your muscle. And then when you gain it back, you don't get back the muscle. Or not as much. You get back more fat. Okay. Yeah, yeah, yeah. And that can happen. Uh-huh. So there is a study in North Carolina where researchers follow people who went through a weight cycle over about a year, lost weight, gained it back.

21:13They found that people lost 74 % of the weight as fat, but when they gained weight back, 88 % came back as fat. Right. It's not a huge difference, but it's definitely there, right? It's there. And you could imagine if you have that difference over time with weight cycling, you're going through this nine times, the fear would be that then it would compound and you would, with every weight cycle, lose more and more muscle. Is that what we see? Well, not every study finds this. So a very similar study from... Oh, Rose, you've done it to me again. Look, you've got to read more than one study. And you've got to tell me.

21:57Then you get... All right. So what's your guess? Okay. Don't tarry me. Let me tell you about this other study. Yeah, tell me about this other study. Great. This one was from Germany. Okay. Researchers similarly followed people when they lost weight and gained it back. Uh-huh. They gained pretty much the same amount of fat as they had initially lost. Same amount of muscle. No real difference. So what, you might ask me, is the difference between those two studies. Yes. That is what I will ask you. What is the difference between those two studies? The difference was age. So in the study where people gained back more fat than they had lost, they were older.

22:39They were people in their 50s, 60s, and 70s. While in the study where people did not really see a difference, they gained back just as much muscle as they lost, they were younger, 20s, 30s, and 40s. And we know that over time, you lose muscle. We all lose muscle, whether we're going through weight cycling or not. That is just one of the ingloriousness of aging. It just happens to everybody. Yes. Yes. So this isn't such a big deal then, you think? I mean, this is a tough one because, and I have spoken to some researchers who are genuinely worried about this. So that's a legitimate concern, but the way people talk about this online, that you're like doomed to ruin your body composition, I didn't see any evidence that that's the case.

23:26Right. But yeah, I mean, and then your question, Wendy, of like, does this compound? Like, does with each successive weight cycle, you lose more muscle, you gain more fat? Yes. I can't really answer that because we don't really have those studies. We have very few studies that follow people for more than one weight cycle. And that's true for all this. Mostly it's just one round of weight cycling. What did John think about this? You know, John said this wasn't something he was actually that worried about. Because from his own experience, he was like, no, when I lose and gain weight, it doesn't really affect, it doesn't seem to affect the way I can operate my body.

24:03Like, he talked about being a drummer. I trust my arms, whatever size I am. Like, I trust that my muscles will do the same thing. Yeah. So that does make sense. I wasn't too worried about that, but I mean, it's nice. Yeah. Like, I wasn't worried about it, but cool, I'll take it. All right, Rose, off to the break. We're going to talk about health more broadly. Inflammation, diabetes, heart disease. Does weight cycling make all of that worse? Coming in.

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