Science Vs - Exercise: Fat Buster or Belly Flop?

Episode Date: September 19, 2019

Lots of people hit the gym to shed unwanted pounds, but they don’t always see results on the scale. This week, we tackle the power of exercise and why you should bother. We speak with obesity expert Dr. Yoni Freedhoff, psychiatrist Dr. Gary Cooney, neuroscientist Prof. Wendy Suzuki and urologist Dr. Stacey Kenfield. Check out the full transcript here: http://bit.ly/2kqreUR UPDATE 10/31/19: An earlier version of this episode said that exercise isn’t a reliable treatment for depression. Some scientists reached out to us about clinical trials we missed. These newer trials found that exercise can help with depression. And we now think the research in this space is stronger than we made it sound. We’ve updated the episode. Selected references: The study which looked at the effect of exercising 5 days a week for a year on weight: http://bit.ly/2mitPR8Gary's Cochrane review on the benefits of exercise for depression: http://bit.ly/2kqrGCxThe study which found that exercise is linked to a lower risk of getting dementia: http://bit.ly/2mj9qeL Stacey's study on exercise and prostate cancer: http://bit.ly/2kuPwgu  Credits: This episode was produced by Wendy Zukerman, with help from Meryl Horn, Rose Rimler and Lexi Krupp. Our senior producer is Kaitlyn Sawrey. We’re edited by Caitlin Kenney and Blythe Terrell. Fact checking by Diane Kelly. Mix and sound design by Peter Leonard. Music by Peter Leonard, Emma Munger and Bobby Lord. Recording assistance from Joel Cox, Andrea Rangecroft, Natalie Jones, and Mark Totti. A huge thanks to all the scientists we got in touch with for this episode, including Professor Virginia Berridge, Professor James Blumenthal, Professor Kirk Erickson, Dr. Tara Walker, Dr. Shannon Halloway, Professor Steven Petruzzello, Dr. Kristine Beaulieu, Dr. Aric Sudicky and many others! A special thanks to the Emmanuel Dzotsi, Zukerman family, and Joseph Lavelle Wilson. Learn more about your ad choices. Visit podcastchoices.com/adchoices

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Quantum Magazine's podcast, The Joy of Why. New episodes drop every other Thursday, starting February 1st. Hey, you guys. After this episode first came out, we heard from some scientists in the field that we had missed some research about exercise and depression. They were right. We are sorry about this oversight, and we've updated that part of the episode to reflect the most current research on the topic. Okay, on with the show.

Hi, I'm Wendy Zuckerman, and you're listening to Science Versus from Gimlet. We are back for a brand new season, and on today's show, we're pitting facts against getting physical. As we look at exercise. Is it like a blockbuster drug or a ball-busting drag? So it is a beautiful Sunday in Brooklyn, New York City.

And I am heading to the park, my local park, to see why people do exercise. All around me, people were sweating their butt off. And when I asked them why, there was one thing that came up again and again. To look good, yeah, obviously, yeah. Not have, like, beer belly and stuff. Shed it. Shed it all. To look good naked. To look good naked. Who are we kidding here? Yes.

But this wasn't just about looking good in the nard. People had all sorts of ideas about the power of exercise. They talked about it like it was some kind of miracle drug. It is a medicine. It is a medicine. And it helps me reduce stress. power of exercise. They talked about it like it was some kind of miracle drug. It is a medicine. It is a medicine. And it helps me reduce stress. Absolutely. Because if not, I'm ready to snap on somebody. Decreases the chance of having cancer. I think definitely it decreases your risk of heart attack.

It's definitely making me feel like I should be running instead of asking questions. On today's episode, we are going to find out which of these things exercise can do and which it can't. Because I'll tell you, some of the things you think exercise works for, it doesn't. When it comes to exercise, a lot of people want... To look good and naked. But then there's science. Science vs Exercise is coming up just after the break. Welcome back.

On today's show, exercise. And first up, we are tackling whether exercise can help you lose weight. Since the 1970s, we've had peppy spandex-clad heroes telling us that the best way to lose weight is to exercise. Let's sweat again! Yeah, you want the perfect bod? Just keep on sweating. Well, I am here to tell you that Jazzercise lied to you. Yeah, so people can lose weight with exercise. It's just that they tend not to lose weight with exercise. This is Dr. Yanni Friedhoff, and he helps people manage their weight

at the Bariatric Medical Institute in Canada. It's Yanni's job to keep up with the latest research related to weight loss. And he says that when it comes to exercise, the evidence is clear. It is not the weight loss pill that we've been promised. Like, he told me about this one study. This was a really impressive study. Basically, what they did was they took sedentary people who were between the ages of 40 and 75. The researchers got around 200 people who barely worked out,

and half of them were told to exercise. And we're not talking some walk among the petunias here. We're talking vigorous exercise, like running or biking. And these people did it for roughly an hour, for five days a week on average, for a year. An hour a day. This is not a week, on average, for a year. An hour a day. Yeah, this is not a small amount of exercise, and some of this exercise was also observed.

Yeah, the researchers actually watched the people in the study to make sure they were exercising. They also gave them pedometers and made them fill out diaries. What they found was that, yes, the exercisers did lose some weight, but perhaps a lot less weight than people would expect. So, vigorous exercise for an hour a day, five days a week for a year. I would expect that after all that time, you'd lose, like, 20 pounds, you know, 10 kilos, something like that, right?

So what did they find? The women lost 1.4 kilograms over the course of the year. So for American listeners, that's in the neighborhood of three pounds. And the men in the study lost around four pounds. That's it. And many, many studies have basically found the same thing. The evidence here is weighty. It's really hard to lose weight by just doing exercise.

And if you still don't believe me, Yoni told me about another study. This one tracked people for 10 years. This is a good one. So this is the Duttenkheim study. How much did you practice saying Duttenkheim? I googled it. You know, being Jewish, the chem is easy too. Great.

So yeah, so the Duttenkheim study, they looked at 5,000 adults for a decade. The researchers checked in on the Duttenheimers to see how much exercise everyone was doing, and they measured their weight. And then at the end of 10 years, they looked at the people who did exercise and those who barely worked out, and there was a lot of unexciting data. So what was unexciting about their data was that everybody gained weight. There was no statistically significant difference between the people who worked out more and those who didn't.

And if you're thinking maybe the numbers on the scale aren't going down because these people are adding muscle, well, Yoni says it's not so simple. So it's a myth that people who are not losing weight in the gym are not losing weight because they're gaining muscle. While Yoni says it is possible to gain a lot of weight in muscle if you do a ton of lifting weights and eating protein, for people doing the casual workout, we just don't gain that much weight in muscle. For those who exercise regularly, especially people who lift weights, to build 10, 15 pounds of muscle, that's a lot of consistent work in a gym. That's not

something that happens quickly. So face it, for most of us, exercise is not a good way to lose weight. And why is this? Well, there are a couple of reasons. Number one, even though we use up calories when we circle those hips, we just don't lose that much. How long would it take me to work off a bagel on a treadmill? You know, I would expect that somebody who's eating, you know, three to four hundred calories worth of a bagel that, you know, has a schmear of something on it, it's going to be at least 40 minutes on the treadmill, you know, at a good clip to see those calories disappear. And there's another problem here. Studies have found that when people think they have burnt a ton of calories from working out? Some of us reward ourselves by eating a bunch more calories. Like one survey of more than 250 undergrads found that around 40% of them admitted too often or always eating more on their exercise days. You put it all together, and for many of us, it's just so unrealistic that

exercise could help us shed a lot of pounds. So why do we have it in our heads that it can? It feels right. There's truthiness to it, right? We're sweating, we're moving, our heart's beating. It feels like it should help. And so I think that we do fool ourselves into thinking that it is having a greater impact than it might actually be having on us. Losing weight is pretty much about what we put in to our mouths. When it comes to weight, I think it would be very difficult for us to outrun a bad diet, especially in the long term. Conclusion. Exercise is not a good way to lose weight. But don't throw out your fancy athleisure wear just yet.

Not that you were using it for exercise anyway. The thing is, even if exercise isn't great for dropping pounds, it doesn't mean it can't turn your day around. Like, you know, make you feel good. And that takes us to our next question. Can exercise improve your mood? We talked to Gary Cooney about this. He's a psychiatrist at Forth Valley Royal Hospital in Scotland. Yeah, well, I think kind of like a lot of people, I had this sort of feeling that, well, it must be good for your mental health. You know,

I certainly find myself when I go for a wee run or something, I feel like I've got some sort of positive benefits out of it in myself, in my own mood. And definitely, I feel it definitely makes a difference to me. A lot of runners like Gary say they feel good after a jog. And there are studies that back up this idea. They suggest that exercise can improve healthy people's mood soon after they work out. But researchers are taking this idea even further and looking at whether exercise can treat those who have clinical depression. Several years ago, Gary wanted to know if this was true. A lot of the patients he sees in his job have severe depression,

and he said that he'd love to have some more treatments in his arsenal. So he joined a team and dove into the research. So we were gathering all the papers that we could find, all the evidence that we could find that asked that particular question, is exercise beneficial to people with depression? Gary was doing this to create what's called a Cochrane review. And these reviews try to use only really good quality evidence. So we here at Science Versus, we love Cochrane reviews. We do jazzercise to them.

Five, six, seven, eight. The bigger, the Cochrane review, the better the evidence. Like with Gary's review, they chucked out the trials that went for less than a week or where it wasn't clear that the participants actually had depression. And after Gary had his way with scores of studies, six were left standing, involving around 450 people. When it came to relieving depression, there was no statistically significant difference between the people who exercised and those who didn't. You know, there's one line I read once, you know, you're only one run away from a good mood.

And I just think that's so simplistic and it's just not true for a lot of people with severe depression. Since Gary's study came out, there have been a few new clinical trials that have showed that exercise can help people with depression. And one reason that these newer studies might be finding a benefit is that these scientists were really tenacious about getting people to do the exercise. Like in one study, the researchers gave participants free gym memberships and personal trainers who would then hound them if they didn't show up to exercise. And with all of this, they did see a benefit. People reported feeling better. I asked Gary what he tells his

patients. It's worth pursuing. It's worth trying. It's worth seeing if it brings you any benefit. But we are working with a very complex organ, the brain, and it doesn't give up its secrets easily and we're not able to shout from the rooftops of certainty about this being the panacea that we would hope it would be. But I would still do it. If I was depressed, I would see what I could do with exercise, I think. Give it a go. Uh-huh, give it a go.

Yeah, I think so. Conclusion. Some evidence suggests that exercise can help people with depression, so it's worth giving it a go. After the break, how exercise can protect you from the biggest killers around. Welcome back. So we've just found out that exercise is not a miracle weight loss drug. But now, get your running shoes on.

Because there are all these amazing things that exercise can do for your body. Like, it can protect you from the biggest killer in the United States. Killer bees! Jokes. Heart disease. Back in the 1950s, research showed the very first link between exercise and heart disease. Back in the 1950s, research showed the very first link between exercise and heart disease. In a study of bus conductors on London's big double-decker buses,

researchers found that conductors, who would run up and down the stairs on the bus hassling people to buy tickets, well, they had half as many heart attacks as bus drivers, who basically sat on their bottoms all day. Over the next few decades, more and more and more research would come out showing that exercise could prevent heart disease, possibly because going for a run can trigger the release of chemicals

which reduce inflammation in your blood vessels. OK, so exercise, it can protect your heart. But now, researchers are learning that exercise might also protect your brain. To find out more, we spoke with Professor of Neuroscience at NYU, Wendy Suzuki. So how many other Wendy's have you met? Not very many. There's very few of us around. All right, all right. So several years ago, Wendy, number two, was studying neuroplasticity, this idea that the brain changes itself. That was her main focus until she went on a rafting trip

where she unhappily found herself to be the weakest person. There were people, you know, well over 60 years old, but they were much stronger than me. I was like, what is the matter with me? She's like, oh my God, this is so bad. And so that's what made me go back to the gym. Wendy wanted to get strong, so she went to the gym, started working out. But then she noticed something she wasn't expecting. It had to do with her brain. She

thought that maybe her memory and her focus were better after she worked out. And Wendy couldn't help but wonder, could exercise really be doing this? Ooh, I wonder if that's it. And so that was the seed, and I thought, I totally want to study this. She raced to the research and found evidence suggesting that soon after people do aerobic exercise, like biking or running, their focus and attention does improve a little bit. But what got Wendy really excited was the research she found on what exercise might be doing for her brain in the long term.

You see, there is intriguing research suggesting that exercise could play a powerful role in protecting us from dementia. So, for example, Wendy told us about a study published just last year which had been tracking almost 200 women since the 1960s. They were middle-aged, and they asked whether they were low-fit, mid-fit, or high-fit. So when the researchers started this study, they measured the women's fitness on an exercise bike as a kind of proxy for how much exercise they were doing. 44 years later, they came back, found all these women, and they asked how many of them developed dementia.

And what they found was pretty remarkable, especially when they zoomed in on the people who exercised the most. If you were high fit, you were 90% less likely to have developed dementia. High fit. Whoa, 90% less. It's huge. Other research has found that on average for people working out, you see a number closer to 40%, which would still be very impressive if regular exercise made you 40% less likely

to have dementia. But there's a hurdle here. Some really important work still needs to be done to make sure that exercise is the thing that's causing a drop in dementia. Because a lot of these studies that have been done, they're survey-based. So researchers ask people, how much do you work out? And then they track to see if they get dementia. And this means that what we've got here is a correlation between exercise and not having dementia. And it could still be something else about these fit people that's protecting their brain.

After all, you've got to remember that old jazzercise adage. Five, six, seven, eight. The bigger the correlation, doesn't mean the better the causation. Yeah. adage. To know if exercise is actually protecting us from dementia, we really need long-term clinical trials, where scientists randomly pick people to do exercise for decades and then see what happens. And right now, we don't have those trials. But before you say, well, jog on then, one thing that might help us get closer to trusting this link

between exercise and dementia is if scientists knew how exercise could theoretically protect the brain. And there is one very cool idea that's getting a bit of attention. It's from research in mice, and it's this. Exercise literally stimulates the birth of brand new brain cells. In rodents, running triggers the release of what are called growth factors. And they can stimulate the birth of baby brain cells. So, for example, scientists give mice a running wheel.

And it turns out that some mice just love running. So they run and run and run and run and run and run. And then scientists slice open their brain and in it they see brand new brain cells. They can visualise these new cells. They can tell where the brain cells are being born and they can even look at the connections that these new brain cells make once they're born.

Wendy says that this is all happening in a very particular area of the brain called the hippocampus, which is known to be important for memory. And we do have intriguing trials in people, humans, that show that after we do exercise, we do see changes to parts of our hippocampus. So the idea here is that perhaps new brain cells in the hippocampus, born thanks to exercise, make our brain more resilient to aging. So imagine every single time you work out,

there's a shiny new hippocampal cell that gets born. Okay, it's not that quick, but that is the image that I use to motivate me to work out because I want as many shiny new hippocampal cells in my brain as I can get over my lifetime. Without slicing open Wendy's brain, we can't actually see if she's getting shiny new hippocampal cells from exercise. And just generally, we need more research to know if exercise really can get all the credit for the lower rates of dementia. So we're absolutely still working out the details on how to understand all those different to know if exercise really can get all the credit for the lower rates of dementia.

So we're absolutely still working out the details on how to understand all those different complex things that happen with exercise on the brain. But this hasn't stopped Wendy from being an exercise true believer. While studying the effect of exercise on the brain, she even got trained to be a gym instructor. And she has this little ditty that she shares with her classes. I exercise to change my brain because I want it, I want it, I want a stronger brain. Yeah!

Nerd. Conclusion. There's some exciting new work suggesting that exercise could protect our brain in the future by cooking up brand new brain cells. And the final thing we want to talk about is exercise's effect on the second biggest killer in the United States. Quicksand.

No. Cancer. And I know, I know, on this show, we always hear people claim that this or that can protect us against cancer. And we almost always say, yeah, not so much. But this time, it's different. So, is there a link between exercise and lower rates of cancer? Yes. The shorter answer is yes. This is Stacey Kenfield at the University of California in San Francisco.

There are many studies that have been published over the last few decades showing that exercise reduces your risk of getting cancer. That is, like, I had no idea. Yeah, I think overall, most people don't know about the relationship between exercise and cancer. Exercise is linked to a lower risk of getting many kinds of cancers, but the strongest evidence is for colon, breast and endometrial cancer. Studies have found that on average, people who exercise regularly were 20% less likely to get colon cancer and 10 percent less likely to get some kinds of breast cancer. That's according to a big report from the World Cancer Research Fund. And another reason

that we think exercise might help us fight cancer is that scientists are seeing benefits in people who already have cancer. So several years ago, Stacey and her team did one of the first studies looking into this. They looked at more than 2,000 men who had prostate cancer, and her team followed them for almost 20 years. Men who were doing three or more hours of vigorous exercise per week had a 61% lower risk of dying of prostate cancer. Oh, wow. And that number is just huge. When you saw that number, so what's going through your mind at that point? So initially, I was the one that was seeing the data for the first time. It was just really shocking that the benefit of exercise was so great.

Other research in some other cancers has found this too, that doing exercise, even if you have a cancer diagnosis, might help. Now, a lot of these studies that we're talking about, they also suffer from this correlation causation problem that we saw in dementia. So it's important to try to figure out what could be the mechanism here. Like, how could a swim protect you from cancer? Well, there are a bunch of mechanisms that might be at play. But one idea is that exercise could actually kill cancer cells. You see, there's evidence that exercise can unleash these cells that are called natural killer cells. And they can get into tumours.

So Stacey sent me a study in mice who had cancer. And the researchers in that study got their mice to run and run and run and run and run and run and run. And then they looked at their tumours under a microscope. You can see the infiltration of natural killer cells in the tissue. Oh, wow. But in the mice that didn't exercise, there were way less natural killer cells in their tumours.

And once those natural killer cells are inside cancer, they don't mess around. After all, they're not called natural flower cells. So once the natural killer cell identifies a cancer cell, it decides to kill it and it releases chemicals that cause that cell to explode or rupture. That's, I mean, it's so cool. I know there's like lots of potential mechanisms,

but this one is particularly cool. Yeah, I think it's really great. When you're doing your run and you're running like full speed, are you thinking about like, get those cancer cells? I think about it a lot when I'm exercising. Really? I kind of just picture, you know, your body working for you like an army to help you combat disease, including cancer.

Pretty cool. Conclusion. There's some good research suggesting that exercise can help you fight cancer. Pretty cool. Conclusion. There's some good research suggesting that exercise can help you fight cancer and it also might make it less likely that you'll get cancer in the first place. So when it comes to exercise, what is it really good for? One, can it help you lose weight? Not really. Not unless you're doing a ton of it. And who are you kidding? Two, can it cure depression? There is some evidence that exercise can help people with depression, particularly if a trainer is hounding you to actually do it.

Three, what else is exercise good for? Well, a lot. There's growing evidence that it can prevent heart disease, cancer, dementia, and the list goes on and on and on. You know, exercise has benefits to, like, truly almost all other chronic conditions, to arthritis, our cardiovascular fitness. It improves quality of life. It improves sleep. It improves pain. This is Dr. Jonny Friedhoff again, who told us

that exercise is not good for weight loss. But despite this, he's pretty much exercise's biggest fan. It really is a magical thing what sustainable exercise will do if you're growing older and you want to remain functionally independent, wiping your own parts for longer. I mean, these are things that are remarkably important to our lives, but they get shortchanged when the only thing we tend to talk about in regard to exercise is weight loss. If you were to ask me what is the single healthiest behavior a person could undertake in the name of health, it would be exercise. So maybe forget about exercise for shedding a bunch of weight and start thinking about it as doing so much more.

That's science versus exercise. Five, six, seven, eight. Let's science again. Come on, everybody. This episode has more than 140 citations, and if you want to see them, you can click on the link in our show notes or go to sciencevs.show and follow the links to get to the transcript.

Next week, we are taking on America's favourite sport, the links to get to the transcript. Next week, we are taking on America's favourite sport, football. And we're asking, how dangerous is it? That's what I've been dreaming about since I was a little kid, since I was five years old. That's what I wanted to do. I want to be in the NFL. It makes you smile

really broad. Yes, it does. I'm just thinking about if all of that happens, how great my life would be. This episode was produced by me, Wendy Zuckerman, with help from Meryl Horn, Rose Rimler, and Lexi Krupp. Our senior producer is Caitlin Sorey. We're edited by Caitlin Kenney and Blythe Terrell.

Fact-checking by Diane Kelly. Mix and sound design by Peter Leonard. Music by Peter Leonard, Emma Munger and Bobby Lord. Recording assistants from Joel Cox, Andrea Rangecroft, Natalie Jones and Mark Totti. A huge thanks to all of the scientists we got in touch with for this episode, including Professor Virginia Berridge, Professor James Blumenthal,

Professor Kirk Erickson, Dr Tara Walker, Dr Shannon Halloway, Professor Stephen Petruzzello, Dr Christine Bailiw, Dr Arik Sudiki, and many others. A special thanks to Emmanuel Joshi,

the Zuckerman family, and Joseph Lavelle-Wilson. I'm Wendy Zuckerman. Back to you next week.