That Neuroscience Guy - The Neuroscience of Sticking to Your Diet

Episode Date: January 29, 2022

We have all cut corners when making healthy changes. For a lot of us, that might mean eating something forbidden by a diet or skipping a workout. But why do we lose willpower when we need it most? In today's episode of That Neuroscience Guy, we discuss the neuroscience behind maintaining our diets, and where our willpower comes from. 

Hi, my name is Olof Kregolsen, and I'm a neuroscientist at the University of Victoria. And in my spare time, I'm that neuroscience guy. Welcome to the podcast. Have you ever started a diet or exercise program and had a bit of trouble with it? a diet or exercise program and had a bit of trouble with it? You know, we're almost a month into 2022 and a lot of us made some New Year's resolutions. So have you ever skipped the occasional workout or eaten a bunch of food that was on the banned list? I know I have. Over the past year, I've lost close to 60 pounds, and I did it through a bit of dieting, and more importantly, some willpower. Now, recently we did a podcast on the neuroscience of habits, but on today's podcast, we're going

to be talking about something similar, but different. I'll be talking about the neuroscience of dieting. In other words, willpower. about the neuroscience of dieting. In other words, willpower. Now, the traditional take on willpower was centered for a long time around a concept called ego depletion. And I'll say at the outset, that concept is still out there, and it's not a great one to sort of believe in or hang on to. And I'll walk you through that and talk about what's going on in the brain when we are dealing with willpower or our lack thereof. Basically, the idea of ego depletion is fairly straightforward. The theory is that willpower is tied to having a limited reserve of mental energy.

So you only have so much mental energy to get through the day. And if you run out of that energy, you're more likely to lose self-control. So exerting willpower costs you energy under the ego depletion theory. And because you're also exerting energy for other things, at some point you run out of energy and then you're more likely to go for that extra scoop of ice cream or forget to take your evening workout. So like I said, in terms of dieting, it's pretty straightforward. You have started a new diet, and as your day progresses, you're using mental energy for all sorts of tasks, and you need some mental energy to stick with that diet, and you just

run out of that energy, so you might break your diet and have some fried food or eat some ice cream, like I said. The same example is true with exercise under ego depletion theory. You know, you're going through your day and you're expending mental energy and you're planning on going for that run after work, but you're simply just out of mental energy. Your ego is depleted. And so you sit at home on the couch and watch TV as opposed to going to the gym. This even explains why you might reach out to a former romantic partner. Your ego is depleted. You've spent too much energy and you've just simply lost the self-control to exert willpower and say, you know, hey, I don't want to do that. exert willpower and say, you know, hey, I don't want to do that. Now, where did ego depletion come from? Well, basically, the idea emerged in the late 1990s from a group of researchers at

Case Western University, and they ran a bunch of studies. And I'll walk you through one of their classic studies on ego depletion. Basically, they put two groups of people in a room, and there were two plates of food. One of the plates had fresh baked cookies. We all know that smell. And the other just had some radishes. And people in one group, so say you're in group A, could only eat the cookies and people in the other group B could only eat the radishes, or at least they weren't supposed to. They were told to resist eating these foods.

So the people in the radish group had to resist eating those yummy chocolate chip cookies. The idea was pretty straightforward. If ego depletion is a real thing, the people in the radish group would have to use a lot more willpower to not eat the cookies than the people in the cookie group would have to use to not eat the radishes. I guess the idea falls apart if you've got someone that loves radishes like I do and tends to avoid chocolate chip cookies, but I think we all get the concept. Now there is one other key step. Both of the groups got a puzzle to work on. And the key thing to understand about this puzzle is it wasn't solvable. All right, so no matter how much time you worked on it, you just never came up with the right answer.

So, the idea again was simple. You just see which group was going to spend more time working on the puzzle until they give up. And again, I think you can guess the hypothesis. The idea was that people in the radish group would probably give up working on the puzzle sooner because of ego depletion. They simply didn't have the energy to keep working on the puzzle, so they stopped. And that's because they spent so much energy trying to not eat the cookies. And that's what the research team found. And in fact, they found that the radish group gave up almost twice as quickly as the cookie group. group gave up almost twice as quickly as the cookie group. So, evidence is there, problem is solved, ego depletion becomes a key explanation for willpower and lack of willpower.

But here's the problem. While ego depletion became a really key concept, and it's even come out into the public domain, there's a lot of self-help gurus and a lot of people that get paid a lot of money to speak that talk about ego depletion and willpower. Other scientists weren't able to find the effect. In fact, one study had over 2,000 participants in it, and they couldn't replicate the original work. Now, if you think back to our recent podcast on how research actually works, replication is everything. It's not good enough to run a study one time and find an effect, but you need to find that effect again and again and again. In this case, you have to demonstrate that ego depletion is a real thing. Now, let's be clear.

There wasn't just one study on ego depletion. There was a whole bunch of studies done on ego depletion. But a review of those studies that was done in 2010 came to a conclusion. And the conclusion was simple. In science, null results are incredibly hard to publish. A null result would be running this study and not finding ego depletion to be a thing. Now, the reality is that not finding the effect is as valuable as finding it. But because of this bias in science to not publish null results, all of the studies that weren't finding the ego depletion effects were never getting published and never coming to the light of day. And all that was getting published were the studies that were showing the ego depletion effect.

In fact, as I was doing research for this episode, one of the more ridiculous claims that I found was that ego depletion theory also has this sort of spinoff idea that sugar is like a willpower juicer, right? And sugar actually might be good for you. Well, there's a small problem. The sugar you ingest right now, let's say you take a couple sips of a can of Coca-Cola. Well, it takes time to enter the bloodstream, so it's not going to impact you immediately. cola, well, it takes time to enter the bloodstream, so it's not going to impact you immediately. And even more importantly, if you want some brain trivia here, which makes sense given it's a neuroscience podcast, researchers have known for quite some time that the brain does not use more

sugar or blood sugar specifically when working on mentally challenging tasks. Simply put, your brain's an organ, it's not a muscle. So to be clear, the calories your brain consumes throughout the day are the same if you're playing Sudoku or watching a mindless TV show. Your brain is burning the same amount of calories, so pumping in some sugar isn't going to help it function better. So as I've stated, there's a lot of research, especially in the past five years, that's kind of throwing the concept of ego depletion under the bus. the past five years that's kind of throwing the concept of ego depletion under the bus. In fact, recently people have been stating that even believing in the concept of ego depletion might be a bad thing for us. For example, if you believe in the concept, it's more likely that you might lose control and go against a pledge you've made because you're just going to tell yourself, well, my ego is depleted. You know, I guess I'll give in. And that's the current working theory. It's all about

belief. There was some really cool research at Stanford that demonstrated that ego depletion is only observed in people who believe that willpower is a limited resource. People that didn't believe this, people that thought that willpower was something they had lots of, didn't see the ego depletion effects. And it was only people that said, yeah, well, I'm out of willpower now. They're the ones that showed the ego depletion effect. And this is so dangerous because there's so many people out there, like I've said, promoting ego depletion is a thing, which is bad because if you believe in it, you're more likely to lose your willpower.

which is bad because if you believe in it, you're more likely to lose your willpower. So you don't want to believe that willpower is some finite resource that you might run out of. All right, you need to believe that willpower is this thing that you have. Now, it's a little bit trickier than that. And for that, I'm going to go to a colleague of mine and a friend, Michael Inslick. He's a professor of psychology at the University of Toronto, and he's looked into this idea of willpower quite a bit. What Dr. Inslick would tell you is that willpower isn't a finite resource, but it's more like an emotion. So you don't run out of anger or joy, right?

Anger and joy ebb and flow, you know, depending on what's happening in your life. Willpower ebbs and flows based on what's happening in your life, willpower ebbs and flows based on what's happening and how you feel. And if you think about this, that's important. You know, one example I use a lot is think about when you fail your willpower. It's generally when you're tired or something bad has happened. So thinking about it more like an emotion where you have to be aware it's there and it might be up and down is important as opposed to thinking of it as a resource you're going to run out of. So to repeat that again, the short version of this is simple. You need to accept your willpower will ebb and flow, but you will not run out. And if you want some ideas on how to help yourself

have more willpower, it's simple. Take care of your brain. Now, we did a podcast on this recently, so I'm not going to go through that again. But if you remember the take home message, get lots of sleep, make sure you are eating a healthy, well-balanced diet, exercise regularly, engage in wellness activities like breathing, yoga, or mindfulness, and ensure you've got social interaction. All of these things promote better brain health, which means you will have more willpower. Now, I haven't talked a lot about what's going on in the brain so far. I've mentioned a few things, so I'm just going to give you a little bit more about the nuts and bolts of this. The reality is another way you can think of

willpower and these choices you make when dieting or exercising. It's about balancing rewards. So for instance, the orbital frontal cortex, which is right up at the tip of your brain, basically it's part of the brain that evaluates reward values. So when you're making a decision to go for a run or not go for a run, it's a value comparison. Now to expand on that a bit more, and we've talked about this in the past when we talked about social decision making, you might remember that the prefrontal cortex, which includes the orbital frontal cortex, it's going to come up with your logical choices. Go for the run. All right, don't eat that food. It's bad for you. The amygdala and the other emotional parts of the brain, those are the parts of the brain that are going to promote the bad choices in principle. Yes, you feel like ice cream. You're a bit down, eat the ice cream. And there is a third player.

There's the anterior cingulate cortex or the ACC. It's sitting there mediating these choices. And if you are promoting good brain health within yourself, sleep, diet, exercise, mental well-being and social interaction, then the ACC is more likely to side with the prefrontal cortex and the emotional parts of the brain are less likely to impact you. So the take-home message on this is really, really simple. Willpower is not something you run out of. It's something that ebbs and flows like an emotion. And the better you take care of your brain, the more willpower you'll have. And then you'll do a lot better with dieting or exercising or the other things where we think that willpower is a key part of the process.

Thanks again for listening. Two more episodes to go after this one. We're going to drop one on Sunday. And then we have one more after that, the week after. And then we'll be done season two, and we'll be getting ready for season three. We will be taking a couple weeks off. We've got some ideas to help us be more efficient in terms of delivering content every week on a Sunday, and we're going to implement those. Now, remember, you can also follow me on Twitter.

You get updates about what's going on in the Craig Olson lab, my lab, and stuff that I think is cool in neuroscience, it's that Neurosci guy. We also have YouTube. It's not much there. I've mentioned this a couple of times, but we are going to port over a bunch of content I have from another YouTube channel.

We just got to do a bit of rebranding. So starting with season three, we're going to have a whole bunch of really cool content, mostly on learning and decision-making to start with, but we'll be expanding that out. Remember, you can email us ideas. We've got a long list from all of you that are listening, and we're going to work through those in our little bit of downtime. Thatneuroscienceguy at gmail.com. We really want to know what you want to hear about in terms of the neuroscience

of daily life. And of course, I mentioned this last week, there's not much there. It's a redirect to my own webpage, but thatneuroscience.com. There's going to be some cool stuff up there for season three, and we think you'll be excited by it. I hope you enjoyed today's podcast on the neuroscience of dieting, aka willpower. Thank you one last time for listening, and we'll see you soon.