Science Vs - Obesity - Is It Your Fault?

Episode Date: December 14, 2017

We’ve always been told to get off the couch and stop eating junk food if you want to lose weight - but is the obesity epidemic that simple? (Spoiler alert: it’s not.) We speak to geneticist Dr Giles Yeo, exercise physiology researcher Dr Lara Dugas, gastroenterologist Dr Jessica Allegretti, nutrition researcher Dr Pablo Monsivais and Italian radio maker Jonathan Zenti, Check out Jonathan’s podcast MEAT here. Check out the full transcript here: http://bit.ly/36jtLCo Selected reading: The 2007 study announcing the FTO gene and its link to obesityThe cute cookie studyThe paper that says ““Let us bust the myth of physical inactivity and obesity”The curious case of the poo transplantFood deserts in DetroitOn fast food advertising  Learn more about your ad choices. Visit podcastchoices.com/adchoices

Hi, I'm Wendy Zuckerman and you're listening to Science Versus from Gimlet Media. This is the show that pits facts against fat. On today's show, science versus obesity. What exactly is making us fat? For the most part, we've been taught that if you're fat, it's your fault. Get off your bum and go for a run. Stop eating so many carbs. That's what Jonathan Zenti has always heard.

The wrong things I do is that I eat, like, huge balls of pasta, I eat pizza and I eat bread. They are my Achilles heels. Of course Jonathan loves those things. They're great. Plus, he's Italian. Jonathan is a radio producer and he's been overweight for a while now and recently documented his weight struggle.

He talked to our reporter Heather Rogers about it and Jonathan said that his mum is always trying to pressure him to eat better. She took me to a fish restaurant because she knows I don't like fish very much. She took you there so you wouldn't eat very much? Yeah. What did you order? I think fried something. I ordered something fried, but just for revenge. Away from the family gripes, Jonathan says that strangers judge him because of his body all the time. I take the train a lot. And when there is someone already on their seat and I come and I say, oh, I'm next to you, like the disgusted face, like, oh my God, I have a fat one next to me.

That's my every time, like 80% of the time I get a disgusted look. And so they try to change the seat. Oh, wow. Yeah. But the thing is that all over the world, people are struggling with their weight. And just to look at America, more than two thirds of adults are now overweight or obese. And this has happened so quickly over the span of just a few decades that it has made scientists wonder if it really is our fault that we're fat. Perhaps something else is going on here that's making so many of us overweight. Like maybe it's in our genes.

And Jonathan has thought about this too. My mother's father was like very chubby. My mother, she's naturally very big, like she's tall and large shoulders and she gains weight very fast. And he said he'd be so excited to find out that his genes were the thing making him fat. It's because of my mother. It's not because I couldn't him fat. It's because of my mother.

It's not because I couldn't control myself. It's genetic. Bye. So on today's show, will the Jonathans of the world be vindicated? For the millions of us who are overweight, we're going to find out if we really are to blame for our bulge. To puzzle it out, we're delving into the following questions. One, is getting fat written into our DNA? Two, if you do get off your ass and go for a run,

will it stop you from gaining weight? And three, we'll tell you about a mysterious force that could be making us fat, and scientists are just starting to understand it. When it comes to obesity, there are lots of looks of disgust. Oh my God, I have a fat one next to me. But then there's science. Science versus obesity is coming right up.

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On today's show, we're delving into this question of whether you really are to blame for your weight. And right off the bat, we'll tell you that generally speaking, the more you eat, the more weight you'll gain. The fact is that your diet plays a big role in how heavy you are. Studies consistently find that when people cut the amount of calories they eat, they lose weight. So, the food you eat, it does matter. Sorry.

But still, this is far from the whole story. So, first up, what about Jonathan's wish that he could blame his mum for his weight? It's genetic. Bye. But is it? Is your DNA making you fat? To find out, we decided to talk to this guy. Hello, I'm Giles. Who are you?

That's Giles Yeo. He's a geneticist at the University of Cambridge in the UK. And he's been researching genes and obesity for around 20 years. And Giles says, yes, you can blame your parents, at least a little bit. Your body shape is powerfully genetically controlled, whether or not you become fat or not. Next time you're at the airport, don't stare too much, you might get smacked. But if you're there with your venti latte,

just look at families that are walking by. And Giles thinks this not just because he creeps on families at airports, but because of studies that have scoured the genes of thousands of people and measured their weight, as well as these impressive studies that have been done in identical twins. In fact, that's what really convinced Giles. Yes, undoubtedly it's the twin studies. You see, if identical twins are always the same weight,

then genes must play a big role in making us fat. But to know for sure that it's the genes, you really need those twins to grow up in different places because otherwise their mum and dad are probably feeding them the same food. But... We do live in an awful world and more often than we might imagine twins are split up at birth and are raised in different places.

Bummer for the twins, great for science. When researchers look at these kinds of twins they tend to find that if one twin was overweight, the other one twin was overweight, the other one probably was too. So from this, we know that a big chunk of how fat we are is based on our genetics. Exactly how much? Well, that varies a lot between different studies. All evidence points to the fact that genes play an enormous role in our body shape and body size. But exactly how are your genes conspiring to make you fat? Well, to explore that, we're going to tell you about one gene. It's called the fatty boomba gene.

No, it's obviously not called that. It's called the fat mass and Obesity Associated Gene, or the FTO gene. Now, there are some types of this gene that increase your risk of being obese. And here's the thing. Some people have no fat versions of this gene, some people have one,

and other people, those at the highest risk of being obese, they have two. What is abundantly clear Other people, those at the highest risk of being obese, they have two. What is abundantly clear is that having one or two fat versions of these genes increases your risk of obesity. And studies have found that a lot of people around the world have these fat genes. And here's how it might be affecting your weight. Giles reckons that these genes make your brain think that you're hungrier than you really are. If you are not hungry, it is very easy to stop eating because you are not hungry.

So there is no willpower, there is no challenge. If, however, you're hungry, it's always going to be more difficult to stop eating. So, for example, researchers in the UK gave kids who had just eaten dinner a plate of biscuits and cookies. And they wanted to see if some kids would eat more than others. Here's what they found. The kids who had two fat genes ate 10 grams more on average than the kids who didn't have any fat genes. And that 10 grams is about the weight of an Oreo cookie. Now, this is an adorable study, mainly because it means we get to say the word cookie.

Cookie, cookie, cookie. Oh! Nom, nom, nom, nom, nom, nom, nom. But the truth is, our appetite is an incredibly complicated thing, and Giles doesn't think that you can solely blame your FTO genes for making you eat cookies. In fact, studies have found that people with two fat versions of this gene

only weigh a little bit more than those with none. If you have two fat versions of FTO, then you're on average three kilograms heavier, or about seven pounds. So having two fat versions means you might only be about seven pounds heavier? What's all the fuss about then? Because that's not that much. But the thing is, that's just one gene. There are scores of genes that have been associated with obesity,

and they might be lurking in our DNA, slightly increasing our risk of getting fat. So, so far, that all makes sense. But it does seem pretty weird to blame our genes for the surge in obesity that we've seen over the last few decades. Because that fat version of the FTO gene didn't just appear out of nowhere. It's probably been with us for a very, very long time. So why wasn't it making us fat, say, a hundred, a thousand years ago? Why are we just getting fat now? Ah, okay. So that's the $64 million question. You're absolutely right. Our genes have not

changed, certainly over the past few thousand years, but it's our environment that has changed. Giles thinks that these fat genes might be holdovers from thousands of years ago when food was scarce and we didn't really know where our next meal was coming from. In an environment like that, our bodies needed to eat whatever food was around and to store that energy for a rainy day. So it's possible that for thousands of years,

these fat genes that helped us to survive are now working against us. Because now, for a lot of us, food is everywhere. Ultimate cheesy crust pizza. 16 cheesy pockets overflowing with a five cheese blend of melted cheeses. And so those once very handy genes might now be helping to make us fat. Conclusion, there is good evidence that genes do play a role in how fat we are. But still, Giles says that these fat genes don't necessarily seal our fate. If you want to consider your genes as a hand of cards in poker, you can win with a bad hand of cards and you can most certainly lose with as a hand of cards in poker, okay? You can win with a bad hand of cards

and you can most certainly lose with a good hand of cards. Okay, so if you're dealt a handful of obesity cards, what can you do about it? Well, something that we all hear is that exercise will do the trick, just like in The Biggest Loser. Tanya, walk that out. Go, girl, walk it out.

There you go. Use those abs. Keep moving. Up and down. I just need a minute. No, Matt, you don't need a minute. Actually, Matt, why don't you take five? Because some scientists have recently called out the idea that exercise could battle the bulge. A group of researchers recently wrote,

let us bust the myth of physical inactivity and obesity, while another team noted that when it came to physical activity, there is limited evidence to suggest that it can blunt the surge in obesity. Now, there is really good evidence that exercise is important for our overall health and preventing chronic illnesses like heart disease and diabetes. Hi, sorry. Hi, Wendy. Lara Dugas, a physical activity researcher at Loyola University in Chicago, told us that there is no debate

that exercise is good for our overall health. That's not the debate we're having. The debate is really about if you are physically active, is that enough to prevent you from gaining weight? Because this is the thinking, right? This is what we've all been told. Right. So we really wanted to investigate this.

When Lara went searching through the studies, she found conflicting messages about whether exercise could actually help with your weight. So she wanted to get to the bottom of this. And Lara wanted to compare people living in different countries. So she studied about 2,000 people from around the world, from America as well as a handful of kind of exotic locations. Yes, I did.

I travelled several times to Ghana, South Africa and Jamaica and I got to the Seychelles, which is absolutely gorgeous. It's beautiful. It's paradise. So some people lived in paradise and some of them lived in Chicago. And Lara has been checking in with the people in her study over a few years. She's tracking their weight and also how active they are. And here's what she found. There was no relationship between the amount of physical activity you were doing

and then the amount of weight that you would gain. So overall, she couldn't find a clear link between being less active and gaining weight. But how is that possible? Well, here's the thing. We know that exercise and physical activity burns calories. But other research tells us that it just doesn't burn that many calories. And Lara says, generally speaking, the physical activity we do in our daily life just isn't enough to burn off the calories that we're gobbling down. In other words, it's just really hard to outrun a muffin.

I talked to Lara about it. You eat a muffin and it's 400 calories and then you go on the treadmill, you run your ass off for an hour and then you see burned 400 calories. That's exactly right. So trying to lose weight by exercise alone, it's not going to happen. Well, there is one caveat here. There are times when you can outrun a muffin, but you've really got to work it. Research has found that you have to do around three to five hours of hard exercise a week for a couple of months

to lose around two kilos on average. That's about four pounds. So you really have to hit this hard. And even then, doing that much work doesn't always mean you'll lose weight. It all seems to come back to the point that, generally speaking, we just don't burn that many calories when we work out. And several other researchers that we spoke to agreed that unless you do a lot of it,

exercise is unlikely to help you lose weight. Conclusion. For many people, exercise probably isn't gonna make the difference between whether you're obese or not. But the experts that we reached out to said that even though exercise probably won't make you shed a lot of weight, it is really important for your overall health. So let's get that spandex on. Okay, so we've chased down the usual suspects, diet, genes and exercise.

But many scientists say there's something else going on. That's coming up after the break. Welcome back. So we've just learnt that jeans might be playing a role in why you're heavy and that while going for a run is really good for your health, it's not necessarily going to melt away those pounds. But there is something else that might be happening here. Because although you might feel like you're in charge of your body, there's actually trillions of little microbes in your gut that could be influencing whether you put on weight. And some of those little microbes come out in your poo. So to find out more, we track down a bit of a poo expert. So I take the stool. It goes literally into a blender, just like you're imagining, a regular blender. That's Jessica Allegretti, a gastroenterologist at Brigham and Women's

Hospital in Boston. Okay, so back to the poo in a blender. I mix it with salt water just to help liquefy it. And then I pass it through a strainer. There's a lot of chunks, if you will, in stool that we sort of need to get out. Like corn? Is that what we're talking about? Corn? Oh yeah. Vegetable matter and any undigested food, certainly. And what you're left with is just a liquid, a broth, if you will, that's really rich in bacteria. A rich broth, eh? Sounds great. None of this has grossed me out or ever has. I'd say the patients, you know, always. Being a gastroenterologist, Jessica has been obsessed with poo for a while, but she's recently started to think that it might be playing a role in obesity.

And for her, that kind of started with this really interesting study that came out a few years ago. It suggested that little bugs in our gut, collectively called the microbiome, could affect our weight. And it was done in mice. Basically, mice were given poo transplants from people who were fat. Yes, it was a human to mouse poo transplant, as you do. Anyway, so after the transplant, the mice started getting fatter. And that was even though they were eating about the same amount of food. The mouse study was really the first study that made me think, hmm, like, what's going on here? Are you actually able to transmit obesity through

the microbiome? So after this crazy mouse study came out, another bizarre gut bug story emerged. And it put more weight behind this idea that gut bugs could be making us fat. There was a patient who gained a significant amount of weight after a fecal transplant, and the donor was her overweight daughter. After getting the gut bugs from her daughter, who was overweight, more than a year later, the mum had gained 34 pounds, or about 15 kilos. Yes, I think there was a lot of hype around that. So to study whether gut bugs really can make you fat, a group of scientists sifted through the poo of more than 150 people. They were looking for differences in the gut bugs of people with different weights. And the scientists found that when people were obese,

their poo tended to have less diversity in its gut bugs. Now, the researchers said that you can think about your microbiome kind of like a rainforest. It's full of different plants and animals, all just different bugs. People with obesity tended to have less variety in their rainforest. It would kind of be like if the monkeys took over and pushed all the other animals out. Yes, exactly, exactly.

And sometimes when this happens, you might lose some really important creatures. So, for example, Jessica told us that we know that gut bugs can do a lot of different things. They can help us break down the food we eat, and they might even help make us feel full. It's a kind of crazy idea that gut bugs can make you feel full, but here's how Jessica thinks it might work. When certain foods reach your gut, some bacteria trigger a process that then releases this hormone, telling your brain that you've had enough to eat. But for someone who doesn't have so many of those bugs around, well, what can happen?

So what that would mean is that as they're eating and they're digesting their food, they're not getting the same signals that say, you are full, stop eating. They're not necessarily feeling as satiated as they eat. And that's because of the gut bugs. Correct. That's pretty amazing. So the studies we have on the microbiome and obesity are super interesting, but a lot of this work has just been done in mice, so not people. Plus, Jessica says that when we do

look at people's gut bugs, we often don't know what came first, the crappy bugs or the obesity. I think it's a little bit of a chicken and an egg conversation. Still, based on the research that we have, we asked Jessica, when it comes to weight, how much do our gut bugs really matter? And she just couldn't get enough of those egg analogies. I think microbiome is certainly important and likely playing a role, but I don't know that we can put all of our eggs in the microbiome basket, if you will. But do you think at least one of the eggs in the obesity basket can be microbiome? Yes, I do think certainly at least one egg in that basket. Conclusion. Our gut bugs might be helping to make

us fat. They could be interfering with the way that we break down food and how full we feel. But this is such a new area of research that it's just really hard to know how important they are. Let's not count out chickens before they hatch. Okay, so let's move from what's going on inside our bodies to what's happening outside. With obesity affecting so many people, some scientists have found it hard to believe that the problem is just coming from individual stuff like your DNA and your diet. They're thinking maybe it's something bigger than that. Maybe it's our cities and our towns that are making us fat. After all, if you look around, things have really changed. Our cities are more spread out,

there are more cars and fast food joints. And these researchers thought to themselves, aha, maybe this new environment is what's causing this explosion in obesity. There are streets in England, for example, where half of the shops are fast food shops. That's Pablo Monsivias. He studies nutrition and obesity at Washington State University. And Pablo, he's got a list of suspects of things in our neighbourhood that might be making us fat. Let's start with suspect number one.

I'm at the combination Pizza Hut and Taco Bell. Yes, fast food restaurants. Research has looked at whether people who live close to lots of fast food places are more likely to be fat. And, well, some studies do find a connection, but some of them don't. And on the whole, there doesn't seem to be a strong link here. But the research is still relatively new.

I mean, this isn't the kind of research that is easy to do. Either way, though, from what we have, it tells us that this isn't as clear-cut as just blaming the McDonald's next door. But maybe it's the food that we're buying elsewhere, like from our grocery stores. Researchers looked around and they said, gee, some of these neighbourhoods don't have a good supermarket.

There's no fresh fruit or veggies around. You might have heard of this. Researchers call them food deserts. Well, food deserts are the kind of label that researchers came up with to describe a situation where people living in neighborhoods, and usually these were areas where there's poverty, didn't have access to a supermarket or a grocery store, and oftentimes there really aren't many other fresh, healthy food options.

In Detroit, several areas have been declared food deserts by the US government. But a recent paper analysing obesity rates around the Motor City found that food deserts were rarely in the places with the highest rates of obesity. So the researchers concluded that, quote, food deserts are not a strong indicator of obesity, end quote. Other work from around the US and even the UK has backed up this idea. Overall, the research hasn't found a clear link between how close you live to a supermarket and whether or not you're obese. What they found is kind of a disappointment. And to Pablo, it was disappointing because researchers still don't have that silver

bullet that could end the obesity epidemic. And so some researchers have started looking at the economics. They figured junk food is so cheap, maybe people were eating it because they couldn't afford healthier food. In other words, if you've got $15 a week to spend on groceries, you probably aren't going to be spending it on lettuce because lettuce doesn't really fill you up in the same way that something like bread, pasta, and things that have, in a sense, more energy containing, more calories for your dollar.

And here, studies have found something. Healthy food is more expensive, on average, than junk food. And then if you zoom out beyond people's shopping habits, other work shows that when people face economic hardship, like they lose a job, for example, they do tend to gain more weight over time. But here's the thing, poverty actually isn't consistently linked to obesity. Yeah, despite the stereotype of poor people being fat, having a low income doesn't clearly increase your risk of being obese. According to the Centers for Disease Control and Prevention, in the US, obesity rates for men don't really seem to be

linked to income, though wealthier dudes actually tend to be slightly heavier. With women, though, it's the opposite, and women at a lower income are more likely to be obese. So what does Pablo make of this? It's really clear that it's a bunch of pieces of a puzzle. It's not like smoking and lung cancer, for example. And I think this is true for anything that's, any health condition that has a social origin. You're not going to find one clear slam dunk result that tells you everything you need to know.

Pablo says there's just so much going into what we choose to eat that it's much bigger than our neighbourhoods, so a lot of other things matter. For example, all the junk food ads that we're exposed to, which are a lot. According to a report from the University of Connecticut from a few years back, McDonald's spent almost three times as much

to advertise its products as all the fruit, vegetable, bottled water and milk advertisers combined. And so we're still learning how all of this fits together. Conclusion. We don't really know whether where you live increases your chances of being fat, but there might be a link between financial stress and your risk of being obese. So when it comes to science versus obesity, does it stack up?

Well, the food we eat is absolutely responsible for making us fat. But there are other factors at play, like our genes. They do have a hand in whether we're at risk of being obese or not. Exercise is great for your heart and your overall health, but unless you do a lot of it, it's unlikely to make you thin. Your gut bugs might be affecting your weight, but we need more research to know how important they are. And finally, does where you live make you fat?

Well, while a lot of researchers are really excited about this possibility, the evidence just isn't there. So, is obesity our fault? Well, we are the ones putting the fatty things in our mouths. But there's just too many of us affected by this, too quickly for all the blame to be on people's choices. But what is the main culprit then that's making us fat? Well, Giles Yeo, our genetics researcher...

Hello. ...likens it to a famous mystery. And so the murder on the Orient Express, as we know, the movie is coming out now, so I don't want to put spoilers for people who don't know anything about it. Yeah, just fast forward 15 seconds if you haven't seen it. But for everyone else, here's a reminder. The plot is this. There's a detective on a train and...

Some dude died. Okay, somebody got murdered. Now, in our version of this story, that dead dude is obesity. And there are a bunch of suspects that could be responsible. The food we eat, our genes, our gut bugs, maybe even our environment. Every one of the other 12 passengers had motive and had a hand in the person's death. So trying to blame any one different factor is always going to be very difficult and probably too simplistic and probably wrong. That's science versus obesity.

This episode has been produced by Heather Rogers, Shruti Ravindran, Rose Rimla and me, Wendy Zuckerman. Our senior producer is Caitlin Sorey. We're edited by Blythe Terrell. Thanks also to MR Daniel. Fact-checking by Michelle Harris. Sound design by Martin Peralta and Bobby Lord. Music written by Bobby Lord.

Recording help from Katie Cloxon, Adam Campy, Debbie Lockwood and Heidi Pett. For this episode, we also got help from Dr Yoni Friedhoff, Professor Martin White, Bonnie Ghosh-Dusticker, Dr Melanie D. Hingle, Dr Mike Statton, Dr Nia Mitchell, Professor Pedro Halal, Lillian Bussell and Fancy Feast. And be sure to check out Jonathan Zenty's terrific new podcast.

It's called Meet. Now, this is our last show of the season, so we wanted to give a big thank you to everyone who's helped in all their little and very big ways. An extra big thank you to Leah Rogers, Yvonne Stamatoska, the Sorry family, Ellen Thomas, the Coleman family, Mary Duhon, Simone Chauchard, Amanda D'Souza, Joseph Lavelle-Wilson

and all the Zuckerman family. Thank you, guys. Over the next couple of months, we'll be hard at work to make you another batch of Science Versus episodes. Yes, we'll be back in March. Hit us up on Facebook or Twitter with topic suggestions or just to say hi.

In the meantime, keep an eye out because we'll be dropping some special content down our feed. See you soon. It's been a very fun season. You have to imagine here that you're inside the testicle, right? As I do regularly. See if that works for you. I'm so sick of juice.

Juice is disgusting. You'd scoop out the matter, which was this kind of cowpox, liquidy, thick stuff, and you'd smear it into the cut. Presto, you've now vaccinated that baby. It's like completely bald,

like one of those rare, exotic cats. World Without Pollinators is going from Oz to Kansas. And how much of this is to do with the patriarchy? Patriarchy. Oh, jeez. I'm Wendy Zuckerman. Back to you soon-ish.