Conventional weight loss advice often revolves around counting calories. However, although caloric intake does have a high correlation with weight gain—or loss—the counting approach hasn’t proven effective for most people. Neuroscientist Dr. Stephan Guyenet shares what is more likely to work: shifting your food quality and food environment. By understanding common craving triggers and how your brain causes you to feel full, you can painlessly lower your caloric intake. Get his tips for best results in this episode.
I started finding out that eating behavior and obesity has a lot to do with the brain. In fact, the brain is really the central organ to understanding eating behavior and obesity. For my postdoc, I moved into studying the neuroscience of obesity. We were working with animal models and trying to understand the brain circuits that regulate body fatness and how those get modified in the context of obesity. And during the course of this whole journey, I was learning things that I felt were both very informative, and also not widely known in the public. I was coming across all this information that I thought was so incredibly informative, and was common knowledge in my field of science. Yet, these questions were still being asked in the public sphere. The information really wasn’t out there, and people seemed to have little idea of what was going on.
So I decided to try to move some of that knowledge from the scientific sphere into the public sphere. And I got a lot of traction doing that. People seemed to respond really well to me writing about it on my blog. And ultimately, I turned it into my book, The Hungry Brain, which was the first general-audience book that I’m aware of to focus on the cause of overeating and obesity from a brain centric or neuroscience perspective. I consider myself to be quite lucky to be the first person to crack open that topic in a somewhat comprehensive way to a general audience.
I also want to mention while we’re on this topic that I’ve started a website called Red Pen Reviews that publishes expert reviews of health and nutrition books. Basically, we’ve completely redesigned the book review process and created a structured, semi-quantitative review process that actually numerically scores books on scientific accuracy, reference accuracy, and healthfulness. And gives you basically a score bar at the top of the page that you can check out and very efficiently get useful information about the information quality of a book. This problem that you’re talking about is huge problem, and that’s the initiative that I and some other nutrition scientists have started to begin to address that problem.
If you’re someone who has low scientific standards, you could make what looks like a compelling argument for fiber to sell someone on using that fiber to lose weight. But if you were disciplined and you are not cherry-picking the data and citing the highest quality data for that realm, it’s much more difficult to formulate a misleading argument. However, it is difficult for a layperson to be able to determine the difference between what looks like a scientific reference and gobbledygoop in terms of the reference itself. To determine this PubMed abstract is better than the other one. So what you are doing is hugely helpful for the consumer. You’re allowing the consumer to outsource that to you, so as to be able to assess the veracity of given claims. And I think that’s just fantastic.
Some people will tell you calories in and calories out is an antiquated model. It doesn’t matter. Calorie restriction or deprivation diets don’t work in the long term. People lose weight and then they regain it. And then other people would have you believe that you need to be following a calorie-restricted diet. I think there’s some nuance here, but I’ll hold that. I’m curious to get your thoughts starting from a high summary level, does there seem to be a good correlation between calories in and body composition, or is it not that direct?
That’s not to say that there is nothing other than calories that impacts body fatness. There may be other things. A lot of these studies that have been done, they’re just not giving us very precise estimates, they’re not quantifying precisely what the impacts and different factors are. And we haven’t tested a whole bunch of different factors. I’m not saying that there can never be anything about food other than calories that can impact our body fatness, but that’s the only thing that’s been really convincingly demonstrated right now.
I want to take a step back here because I think people tend to conflate two different concepts as part of this debate. There is the concept of the mechanism. Like what is the mechanism by which food impacts body fatness? And then there’s the concept of what is the best practical route to losing body fat. And those are two different questions. Calories are more useful, I believe in one context than in the other. Calories are very useful in explaining the mechanism by which weight loss diets work. Any weight loss diet, if you accurately measure the number of calories people are eating, that number goes down as they lose body fat. In very tightly controlled situations where you’re reducing people’s calorie intake, their body fat goes down. It doesn’t matter whether you’re reducing that out of carbohydrate or out of fat, none of that seems to matter very much. The main thing that matters is calories.
It’s possible that protein matters a little bit, but even that doesn’t seem to have a big impact. On the practical side, there’s another question. And I think this is the question that people tend to focus on, which is, is just telling people to eat less an effective way of losing weight? I think that is where the answer is closer to no. And it doesn’t mean that it’s not effective at all. We all know somebody probably who just sat down one day and said, “Hey, I’m going to do some portion control and I’m going to eat less.” And they lose 10 pounds. Probably most people know somebody who’s like that. And the truth is you can lose some amount of weight that way, especially for people who are very diligent. Like those in the bodybuilding world for example, who really track their calorie intake. The main thing that they’re managing is their actual calorie intake and their protein and they manage to get their body fat level where they want it by doing that.
It’s not that it’s impossible, but I think the question is what is the easiest and most sustainable route for most people? I think just trying to manage your calorie intake, trying to track and reduce the number of calories that you’re eating without changing the types of foods that you’re eating, for most people, is not going to be the most effective strategy. Particularly in the long run. I think the biggest gains that people are likely to see are going to be via modifying the quality of the food that they’re eating, and the food environment that they’re living in. And allowing those factors to naturally reduce the number of calories that they are spontaneously eating.
In other words, depending on what you’re eating, it could take you more or fewer calories to reach fullness at a meal. By changing the types of foods you’re eating,
you could be full at every meal, but just naturally eat fewer calories. So that’s what I’m talking about as the alternative strategy to tracking calories . You start with the food and food environment and structure it in such a way that you’re eating less. The mechanism is still calories as far as we know. However, you’re not focusing on the calories in your implementation of that strategy. So that’s really the distinction I’d like to make.
I think there’s a grain of truth in a lot of what everyone is saying. But I think in some of this discussion, there’s not a lot of clarity about what level of analysis people are talking about.
The Impact of Food Quality
DrMR: It does look like there’s this emerging theme of food quality being the most important factor to focus on first. I’m thankful for the conversation we had recently with Christopher Gardner, who published the DIETFITS trial which essentially found if you have a high-quality food diet, it doesn’t really matter if the macronutrients are higher carb or lower carb. People tend to lose weight. One of the mechanisms there is likely as food quality improves, overeating decreases. So calorie consumption goes down. Any specifics beyond the basics that are important regarding food quality? Obviously fresh whole foods, fruits, vegetables, meats, seafood, healthy fats and avoiding things that are processed. Added sugars and such. Are there any other important things there that are left out of the standard ‘eat quality food’ description?
DrSG: So I would say that eating whole, minimally refined, minimally processed foods that you’re cooking in your own is a really good high-level rule of thumb that covers a lot of the things that help us eat less, or I should say that help us eat a more appropriate number of calories. Because of course, not everyone needs to eat less. If you want to get more granular and you want to optimize more, there are certainly other things that we can focus on.
For example, we have a pretty good idea of what aspects of food promote satiety or fullness at a meal, what properties of food cause you to either feel more full or less full per number of calories that you eat. It’s interesting because intuitively we have this idea that we just sit down to a meal, we’re hungry. So we start eating, and we keep eating until our stomach is full and then there’s no more room and you stop eating. But that’s not actually the way that satiety works. Typically, at the end of the meal, there’s still tons of room in your stomach. The human stomach is actually pretty massive. You can fit a lot of food in there if you really wanted to.
What happens is that the feeling of satiety is not coming from your stomach. It’s coming from your brain. So basically that feeling of fullness when you lose your motivation to eat, food stops tasting as good, and you have that sensation of fullness. That is the result basically of your brain deciding that you’ve had enough as a result of this monitoring process that it’s doing of what’s going on in your digestive tract. So as food enters your stomach and your small intestine, all these signals go back up to your brainstem via a nerve called the vagus nerve to a part of your brain called the nucleus tractus solitarius. .
The Satiety Center
That is what I call the satiety center. It integrates these really complex signals that tell your brain about the type of food you ate and the volume of it, and all kinds of chemical composition of what you ate. All that information gets integrated into this signal of fullness basically that gets broadcast to the rest of your brain that coordinates all the things that are necessary to cause you to eventually stop eating once that signal builds up enough. So with each additional bite you take, that signal builds up more and more until finally, your brain says, “No, I’m done.” And you go do something else.
So what causes your brain to get to the point where it says you’ve had enough? Well, it turns out that it’s only loosely correlated with the number of calories that we eat. And that’s cool because it allows us to tweak things such that we can get the same sensation of fullness from fewer calories. And we know what properties determined this. The first one is calorie density. So in other words, the number of calories per gram of food or per volume of food. And you can think about this in terms of the difference between a handful of saltine crackers and a bowl of oatmeal. The bowl of oatmeal has a lot of water and fiber in it, even though it has the same number of calories as the handful of saltines. It’s going to occupy a lot more space in your stomach. And it’s going to create a greater sense of fullness per unit calorie. So you eat the same number of calories, you’re going to feel more full from that oatmeal. So that’s called calorie density.
Another factor is the protein content of foods. So most people know this, protein is more filling. For each calorie you eat of protein, you’re going to tend to experience more fullness than from fat or carbohydrate. The next thing is fiber. Higher fiber foods tend to be more filling per calorie. So if you’re eating more vegetables, whole grains instead of refined grains, that sort of thing, you’re going to experience more satiety. And finally, palatability or how good a food tastes. If a food tastes really, really good, it actually fills you up less. There is evidence that in the brain what happens is basically that your pleasure centers shut down a little bit of your satiety. When they’re firing they say, “Hey, satiety center, let’s not feel too full here because this is a really great food. So let’s get some more of it into the body and let’s not feel full just quite yet.” So the better the food tastes, the less full we feel per unit calorie. Basically if we look at all things that we intuitively view as junk foods like candy bars or cookies, ice cream, pizza, all of that stuff tends to have these properties, high-calorie density, low fiber, high palatability, lower protein. Whereas foods that we think of as healthier and more slimming like fresh fish or vegetables, fruits, whole grains. Those tend to have the opposite properties that are more filling.
I think this concept actually captures a significant amount of what it is that’s healthy and slimming about some foods versus others. If you compose a diet that is based on what I just said, you can eat to fullness, and eat fewer calories at a meal. You’re not causing yourself to suffer in any way in terms of hunger, but you’re still eating fewer calories and losing weight over time. So that’s one way in which we can leverage this stuff to eat a healthier diet and meet our weight control goals.
DrMR: And that that begs an interesting question, which was also posed by Gardner, which was could different macronutrient compositions of a diet cause people to consume those foods differently. For example, some people do well on a low carb diet, while others do well on a high carb diet. Could this be related to the difference in how people consume macronutrients?
Carbs vs. Fats
Does there seem to be any evidence showing that there’s a nuance where people should try if they had to lean their diet in one direction more on the carbs or more on the fat? Is there any evidence showing that certain people would do better on one of those versus the other?
DrSG: Yeah, that’s a great question and one that is fairly hard to definitively answer at this point. On the low-carb and the low-fat diet, there were some people who did really great who lost a ton of weight. And then there were a few people who actually gained weight on each of those diets. And the distribution of how well people did on those diets in terms of how much weight they lost was virtually identical. There is a lot of detail to evaluate in the results, but basically, if you look at the individual responses and the variability there, there were practically the same on those two diets. Did you guys talk about that at all?
DrMR: Yeah, we did. And just to reiterate that for the audience, and this was one of the key points that he made and one of the reasons why I wanted to bring him on the show because it looked like either diet had equivalent effectiveness. I feel like that is very important to reiterate that because there is a belief that one dietary camp is better than the other. And I do think some people tend to do better on different composition of their macronutrients. Yes, there’s some individual variability there perhaps. But it’s not to say that the Gary Taubes camp would have you believe all you’ve got to do is just optimize for insulin by eating low carb and you’re going to nail your weight loss goals. And then the Pritikin camp would have you believe just the opposite. And it seems that it’s not quite that dichotomous. And if you hit the food quality piece and the calorie piece, well actually if you just hit the food quality piece, everything else tends to care of itself.
DrSG: Although I will point out that in this case, they were trying to optimize both food quality and restriction of either fat or carbohydrates. So they were stacking both of those approaches and saw pretty good results. I do like that approach. The whole foods approach really is my go-to. Not to say that by itself, it’s necessarily going to give people the weight loss results that they’re looking for if they have obesity or a lot of excess fat mass. But I think it’s certainly a great place to start for most people.
Here’s the complication. Is in any study like this, you’re going to get variability between individuals. Even if your intervention impacts everyone identically, you’re still going to get variability just because of random things that are happening in those people’s lives.
Let’s imagine for a moment that a low carb diet has the same exact weight loss effect in every individual. If they were implementing it identically, it would have an identical effect on everyone. Those people still have other things happening in their lives. Like maybe they’re getting ill and losing a couple of pounds, or maybe they started a new job and there are donuts in the break room every day or they are more sedentary. There are a million different things that could be going on in these people’s lives. Further, these are free-living people that could be implementing these diets to different degrees. Which makes it hard to look at those data and say these people strictly speaking are responding differently to the diet itself.
That said, my best guess is that yes, they are actually responding differently to those different diets. I don’t think we have strong scientific evidence to demonstrate that right now. But I think given human variability across just about everything and the fact that we’re seeing this kind of variability in those types of studies. You also hear plenty of anecdotes of people saying, “I tried a low-fat diet and I was doing the whole food low-fat diet and I just gained weight. And then I went on low carb and suddenly now I’m losing weight, and my appetite is under control. I feel great.”
I actually regularly get emails from people who say the opposite as well, who say, “I appreciate your alternative perspective. It allowed me to consider the possibility that low carb wasn’t the end all be all. I was gaining weight on a low carb diet. I tried cutting the fat back and eating a lower-fat, whole food diet. And now the weight’s coming back off again.” And just to be clear, I’m not claiming that that is the typical response, or everyone has that experience. But that is an experience that I hear from some people and that I’ve heard on a number of occasions.
Putting this all together, I think I would be very surprised if there was not individual differences in how people respond to low fat or low carb diets. But we haven’t rigorously demonstrated that with data, although in principle it is possible to do so. For me, the question is, what is driving that? What’s the physiological impetus? I think that there are probably going to be physiological differences between people that cause them to respond differently to different diets. Just like people respond differently to different drugs, people respond differently to sunlight exposure, people respond differently to psychological stress. We are just all different in various ways.
There are people, like Chris Gardner, who are trying to figure out what physiology might underlie that. And the DIETFITS study basically came up empty-handed on both insulin secretion as an explanation and a few genetic markers related to a couple of different aspects of metabolism.
My guess is that, someday, we will have markers that will be able to tell you whether you’re going to be able to do better on a low-carb or low-fat diet. I expect we will have a series of blood markers and perhaps even more effective, genetic markers. If we can do a large scale genetic study on this, I’d be willing to bet megabucks that we would be able to find a number of genetic markers that together would have some predictive value over whether people will do better on one diet or the other.
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The Food Environment
DrMR: We’ve talked about food quality. We’ve talked about selecting satiating foods. Is there a third in terms of okay, now someone has gotten those two habituated into their diet. What would the third to this be?
DrSG: I think there’s more than three, but certainly, another really important one that I think about is the food environment. You can have a diet that is composed of the healthiest foods around. But if they’re under your nose all day and you’re constantly being reminded of them through smells and visual cues or other people eating them around you all the time then you’re probably going to eat more calories than if you were only receiving those queues at mealtime.
Let’s say you’re in a place where if you wanted to eat food, you would have to walk up a couple of floors and down a long hallway to the kitchen and then microwave something for a few minutes. That’s the only way you’re going to eat food. If that’s your situation, you’re probably not even going to think about food for most of the day.
DrMR: That’s probably part of the reason why food quality is so impactful because it’s much harder to cook your own food rather than just going into a restaurant and saying, “I’ll have one of those and two of those.” It’s so easy to overeat when someone else is making the food for you.
DrSG: Absolutely. Of course I recognize that it’s often difficult for people to cook from scratch. But I think that is the ideal that we should aspire to and try to work toward.
DrMR: Are there any other tips that you found helpful? Obviously, not having a bag of M&M’s in your desk drawer. But any other tips or tricks that you found are little things people do, maybe they don’t realize they’re doing them, where they made these couple food environment changes?
DrSG: Yes, absolutely. Let me just explain a little bit about how the brain reacts to the food environment. Because I think that helps frame this whole thing. So essentially, what your brain does is it builds these motivational associations between cues and rewards. Let’s say you smell brownies coming out of the oven. For most people, that’s a very potent stimulus, right? You’re smelling the brownies which is going to trigger your desire to eat those brownies which is then going to trigger a craving. Maybe you’re going to start to actually feel hungry, maybe you’ll start salivating. That’s because you have created a reward association in your brain via previous consumption of brownies. So basically, your brain comes to associate all the good stuff in the brownies, the sugar, and the fat, and the starch and all that, with the smell of brownies. And once you’ve done that a few times, your brain immediately recognizes that smell and it says, “Oh, that smell means I’m going to get all this amazing stuff.” So it starts triggering these non-conscious motivational processes in your brain.
My book spends a lot of time talking about how this works. But the reason I’m explaining this is I want people to understand that this is a non-conscious process that we, by definition, don’t have a lot of conscious access to or understanding of. It’s just something that wells up from inside us when we experience those cues. For that reason, we don’t have a lot of intuitive insight into what’s going on. So that’s some of what I’m trying to do is increase our insight into this process so we can understand it and manipulate it. The bigger picture is that there are many different types of food cues that can trigger the same process in your brain. This is a process that revolves around dopamine release. Most people in the audience have heard of this chemical dopamine that underlies a lot of the motivational processes in the brain. It underlies our cravings for drugs, food, sex, etc.
So the dopamine release is generally triggered by sensory cues in your environment; the sight of something, the smell of something, thetaste of something, the touch of something. If you’re in your kitchen and you smell those brownies, suddenly you’re going to want brownies. If you didn’t smell the brownies, you wouldn’t want the brownies. If you see a bag of potato chips on your counter, that gets your dopamine spiking and you’re going to want to eat those chips. And again, you’re not necessarily very aware of this, you just noticed that you want to eat chips. But that want was triggered by that sensory cue hitting your brain and triggering dopamine release. So if you get rid of the cues, you can reduce that motivational drive and that craving. And even to some degree, the hunger to a considerable degree. I would say the first thing to do is just have a clean food environment at home and, ideally, at work. I realize sometimes work environments are hard for people to control. But to the extent that you’re able, don’t give your brain those cues that trigger your instinctive desire to eat, that feeling that wells up inside you to eat those foods. Often, types of foods and amounts of foods that are not consistent with your own goals for yourself.
So create that clean food environment. And ideally, the really problematic foods that you have a hard time controlling shouldn’t be in your house at all. I’m not saying to never eat those foods. But if you don’t have them in your house, not only is it physically harder for you to eat, but you probably won’t even crave it. Because when your brain knows that ice cream is in the freezer, in the back of your mind, it always knows that that ice cream is there. And you’re more likely to actually have a desire for it. That could be enough to trigger that dopamine release. Whereas if there’s just absolutely no possibility that you could have that, you likely won’t even experience a craving, won’t even want it.
This is very analogous to cigarette smoking cessation. Of course, I’m not saying that eating a brownie is as bad as smoking cigarettes. It’s not. But, it’s analogous in the sense that cigarettes work by spiking dopamine in the brain. And when you’re trying to quit smoking, you want to remove yourself from all those cues that trigger your desire to smoke. It’s the exact same process. You don’t hang out with your friends that are smoking. You don’t go into the convenience store where you used to buy cigarettes. You don’t leave a pack hanging around in your house. You don’t go to places where people are smoking. You don’t expose yourself to those cues that get the dopamine spiking, that get the motivation going. And again, that’s just an analogy to explain how it works with food as well. So I would say, try to create an environment where you’re not exposing yourself to those visual or smell cues.
And also food advertising. The average American adults sees 20 food ads a day on television alone while the average adolescent sees, I think 16. To the extent that you’re able to reduce that as well.
What’s in Your Toolbox?
DrMR: Not to say that this is a definitive hierarchy, but would tracking calories come in around fourth if you’ve got these other items situated and you’re still not at the weight you would like? Would you say one of the next most fruitful changes is to start tracking your calories so you can see how much you’re actually eating?
DrSG: Well for me, I would probably put that a little bit lower on the list. And I don’t want to give people the wrong impression. I’m not against tracking calories. I think there are a lot of people that can and do it successfully. So I don’t want to knock it. But the thing that I question is the long-term sustainability for the average person. The people who I see that do that really successfully are really focused and motivated people, like people who are figure athletes. I think for the average person who just wants to shed some weight and look better and feel better, I think once you get to the one year mark or the two-year mark, it’s going to be tougher for them to be sustainable about that. The unfortunate truth is that whatever path you choose, it has to be sustainable because if you stop doing it, you’re going to regain that fat most likely.
In terms of the general toolbox, I would say that we have to eat a whole food diet. We have to clean up the food environment. We have macronutrient restriction, which can certainly be helpful. We have regular physical activity. We have better sleep, stress management. I think those are potentially useful avenues for some people as well.
I certainly think that calorie restriction is in the toolbox. I’m just not sure that it’s something that I would recommend as a primary tool, but that’s my opinion. I know some people use it effectively.
DrMR: Now, let’s dig into the calorie restriction a little bit. Because one of the things that I’m wondering about is I’m assuming there’s a decent amount of people listening to this who have probably seen their weight improve from much of the above that we’ve already outlined. And they’re wondering what might they be missing? So perhaps for some people, they’re going to do a better job with their food environment or focus a little bit even more attention on food quality. But one of the things I’m increasingly curious about is would a short-term intervention of tracking calories help someone recalibrate their diet? Has someone fallen into, and this is something I actually experienced myself. I fell into a pattern where it looked like I was eating about five to 800 calories too much many days of the week just because cheese, healthy grass-fed raw cheese was something I was incorporating in my diet. But at the end of the day, I would just overindulge in that.
So the tracking helped me figure out okay, right now I’m doing about 3,000 calories per day. It took me a month or two of tracking to recalibrate and settle into that rhythm and let my cues re-establish. So now I’m wondering, do you think that is a fruitful application? More so tracking in the short term to recalibrate. Then once someone’s got a sense, they can just eat in that realm without needing to track everything in the long-term?
DrSG: Yeah, I mean that certainly makes sense. It sounds like it was fruitful for you. This is not an area that I have a lot of experience or knowledge in, but I know that there are some people like Yoni Freedhoff who is a big advocate of having people keep food diaries just to gain a greater awareness of what they’re eating. It certainly makes sense that an approach that would help people gain awareness of what they’re eating and where the problems might lie would be useful. There is a principle that I think could be applied in this case that would have helped you, that is an alternative to tracking calories. Eating less calorie-dense foods. And I think this is something that can be useful for people as an adjunct to the minimally processed foods thing because. Cheese is a gray area. But one thing that’s not a gray area that a lot of people don’t really think about is added fats. So things like butter, and even extra virgin olive oil. They’re not necessarily unhealthy in all scenarios, but they are very calorie-dense. And I think that they tend to encourage people to increase their calorie intake. When you’re thinking about eating minimally refined foods, butter isn’t one you think about. But butter is actually quite refined. With butter, you’re taking 3% of the volume of milk, and concentrating it basically all the fat into this solid chunk. So you’ve taken a fluid milk and you’ve concentrated it down into a food that is virtually the most concentrated source of calories in the human diet.
DrMR: One of the things there that has been problematic for many in the ancestral and paleo realm, is the acknowledgment that fat isn’t bad for you, especially coming out of the ’70s, ’80s low-fat kick. Acknowledging that healthy fats and fats in general (as long as they’re not trans fats) can be incorporated into the diet and are not this universal evil as they’ve been portrayed. Unfortunately, I think the pendulum has swung so far where people are saying, “Well yeah, I put grass fed butter in my coffee and I’m having raw cheese, and then I’m having coconut oil.” As if the more fat you eat, the better it would be. I think that we’ve gone too far in that direction and that is a mistake.
DrSG: I absolutely completely agree with that. I think this is one of the places where we can get some clarity from the animal research literature because there have been tons of diet research studies in a variety of different species using a variety of different dietary factors. And one of the things that is the most consistent that we see emerging from that literature is that added dietary fats increase body fat. You see that across a variety of nonhuman species, including nonhuman primates, pigs, rodents,dogs, cats, and practically every species that’s been tested. If you add concentrated fat to the diet, they will gain body fat.
That’s not to say that we shouldn’t eat any of that ever, or that it’s necessarily unhealthy. But I think specifically from a weight management perspective, we should be cautious about added fats. I don’t think that there’s anything inherently bad about fat in general. But I do think we need to be cautious if we’re concerned about our weight, about how we’re using it. So I tend to prefer whole food sources of fat the same way that I prefer whole food sources of carbohydrates. I would rather eat a piece of fruit than concentrated crystal and sugar. And in the same vein, I would rather eat yogurt, than concentrated butter. So it’s the exact same principle whether you’re talking about carbohydrates or fat.
Understand, I do use some added fat in my cooking. It’s really practical. It tastes good. So I don’t take an extreme stance on this, but I think that that is a lever that we can use to affect our satiety per calorie ingested, and our body fat level.
DrMR: Two questions for you regarding timing. Time-restricted feeding or intermittent fasting, do you have any thoughts there? And then along with that, is eating late at night, is it as bad as some people portray it to be? There seems to be some data there, but then there’s also some data showing that if you just eat one really large dinner, that that can be beneficial. So timing and I guess the timing of meal frequency or fasting, and then the time of day. I.e., eating too late at night. Is there any consensus there?
DrSG: My perspective on this is that the elephant in the room here is all about energy balance. Calories in versus calories out. It has a profound impact both on body fatness and on metabolic and cardiovascular health. The data, I believe, are quite extensive and clear on this.
Essentially, for the average person who consumes too many calories and carries too much body fat, anything you can do to reduce your calorie intake is going to reduce your body fat and improve your health. So intermittent fasting, time-restricted feeding, those are ways of reducing your calorie intake. In so far as they do that, I think they’re beneficial. Now do they have beneficial properties beyond that, that enhance their health properties beyond just the restriction in calories? I think that’s an open question. I mean, there are certainly plausible reasons to think that it might. Likely longer fasts would be more beneficial than shorter fasts. But I think when you look at restricting your eating window, for example, the problem is that if you essentially are prepared to eat at any time that you’re awake during the day, you’re going to eat more calories than someone who restricts their eating window. Because most people will eat almost right up until they go to bed. So they’re having their regular meals, and they’re having one to two snacks between each of those meals. They are eating a lot more than they need to be eating. And if they just cut off part of that eating window, they’re cutting out a lot of those eating opportunities and a lot of that unneeded snacking.
Now in terms of going on a 24-hour water fast once a week, that could have some additional benefits through things like autophagy, which is a cellular process that breaks down and recycles some of the components in your cell. Maybe some things in your cell are old and need to be replaced, and that helps cycle them through. And there’s certainly some research in animals that supports that. I would say the human evidence is still pretty limited. I’ve been considering at some point doing a more extended fast, perhaps once or twice a year. Maybe five-day, one week water-only fast to promote tissue renewal as I get older. It’s not something I’ve implemented yet, but it’s something I’m tossing around.
DrMR: One other question here, and this is shifting gears a little bit. I’m not sure if this is an area you’ve delved too deep into.
The Genetic Hand You are Dealt
I also wonder, just like some people are unfortunate in terms of being given a non-optimal genetic hand. They might have severe inflammatory bowel disease, or other people might have a congenital predilection toward depression. Again, using these terms loosely. Is it possible that some people just have a damaged metabolism? And sometimes I look around at people who are very overweight and I wonder if they were doing all the stuff that I’m doing, would they have the same body composition that I have? Or do some people have, for whatever reason, early life microbiota damage or chemical exposures? Are there some people that have a, I guess you’d call it a disease? And the disease is some type of dysfunctional metabolism.
DrSG: The answer to that question is absolutely yes. We can start with genetics. Some people just have a much harder time controlling their body composition than others. I think we know this intuitively. We know people who eat like crap and never exercise, and somehow manage to stay slim. We know other people who work really hard at it and struggle with their weight. So intuitively, I think we understand that this is the case. A lot of it relates to genetics. I’m sure it’s more than just genetics, but a lot of it relates to genetics. So if you look at the genetics of body fatness, what you find is that between person differences in body fatness. In other words, what makes one person fatter and the other person slimmer in the general population can be attributed about 75% to genetics. Genetic differences between individuals explains about 75% of differences in body fatness between individuals. So genetics is huge. And if you look at the genes, they’re mostly related to brain functions. So basically our brains, the way our brains are put together before we’re even born and the way that they are set up to operate after we’re born by the genes that are being expressed in our bodies has a big impact on what our level of body fatness is. And that is expressed via our eating behaviors. It’s expressed by the regulatory systems that regulate our appetite and body fatness, and the many other neurobiological processes that impact everything related to body fatness. There there are certainly people who are born with much greater metabolic challenges than others.
DrMR: Or could you make the argument also just to try to put a quick positive spin on this, that in a different environment, that thrifty gene if you will, could be considered a really beneficial asset?
DrSG: Absolutely. I mean that’s why those things exist. Those same genes were really awesome for our ancestors and so they got selected. But the problem is that we’re not living in the environment of our distant ancestors anymore. If you go back 100 years in the United States, there was a lot less obesity than there is today. And if you go back a couple of thousand years to our really distant ancestors, there probably was very little obesity at all, except maybe among the wealthy. The reason I say that is because that’s what you see today in non-industrialized cultures. There is basically no obesity.
All of these genes that we have today, they’re the same genes, but they’re interacting with a different environment that is pushing them to cause us to overeat and accumulate fat. And this is basically the premise of my book. These brain regions that our ancestors evolved to help them survive, and thrive, and reproduce in the environment of our distant ancestors now are basically misfiring because they are now in an environment different from what they were evolved for. Those non-conscious brain regions guide a lot of these processes that regulate our food intake, and our body fatness, and our cravings, and our hunger, etc. Those brain systems, they are just getting the wrong cues from our environment and they’re pushing us to overeat. Unfortunately, some people have just inherited versions of those systems that are more susceptible than other people. So we see this big spread in body fatness within the population.
That said, I’m sure it’s not just about genetic susceptibility. It probably is also about what happened when you were developing in utero, early life experiences, microbiome, chemical exposures maybe. Stresses. There’s probably a lot of different things that could go into it from your environment as well. But certainly, genetics seems to be the most important variable.
DrMR: And for people in this challenging position, is there decent evidence for some of these more medical like interventions like the gastric band or the gastric sleeve? I wonder about are there exceptions where these interventions are very helpful, but I haven’t looked at the data closely enough to be able to tell maybe you see, and maybe these interventions are defined as successful because successful is a 30% weight loss that is achieved by six months. But then they don’t follow up at a two-year window and see that 20% of that 30% gain was then lost. Do you have any thoughts there?
DrSG: So if you compare bariatric surgery to other alternatives that are currently available, bariatric surgery is the most effective for weight loss. As far as I’m aware, it’s more effective than anything else at any time point that we’ve looked at. And certainly, there is often regain over longer periods of time. But that’s what you see with diets too. There’s no diet that’s ever been studied by science in any rigorous way that I’m aware of that doesn’t have substantial regain over time. With bariatric surgery, you get huge initial losses, and then you get regain and while that regain seems substantial, it ends up still producing a better outcome than the alternative.
I think I understand why people can feel uncomfortable about it. It’s a surgery, it’s irreversible. It’s a medical intervention. Many people would rather deal with it in a more natural way. But the truth is that most people are just not going to lose that amount of weight by going on a diet. For the average person implementing a diet, even if they’re highly motivated, they’re just probably not going to get there by any other way. And I think that just goes to show you how challenging obesity is to treat. If it were easy, there wouldn’t be any obesity.
DrMR: Yup. No, I agree. And I ask that question just because I try to check my own proclivities at the door where I lean in the direction of preferring natural-based interventions. But I also try to maintain an open mind. From my brief poke into the literature, it did seem like there were some favorable outcomes there. But I’m not that familiar with the body of literature where if I was missing something, I would know it. I just was curious about your take. I encourage people to be open-minded if they’re in a tough situation in that regard.
DrSG: While I’m on the soapbox, it’s also pretty remarkable at eliminating diabetes, type 2 diabetes. So something like 86% of people who undergo a Roux-en-Y gastric bypass experience resolution of diabetes. In other words, they can just eat regular food again and not be on any drugs, and not have dangerous blood sugar levels. That seems to have a lot to do with just the fact that it’s calorie restriction and fat loss. I think if you could achieve that level of calorie restriction, fat loss on a regular diet, you could probably reverse your type 2 diabetes on a regular diet too. I just think it’s very hard to do that sustainably without the surgery because of how the surgery changes your gut-brain communication. I’m not trying to convince anybody to do that who doesn’t want to do it. But I think when you really step back and take an objective look at the data, that is what they say.
View Dr. Ruscio’s Additional Resources
DrMR: Will you tell people again about your book and then if there’s anywhere else you want to point them to, Red Pen or anywhere else? Please let people know where they can learn more from you.
DrSG: Yeah, so my book is called The Hungry Brain: Outsmarting the Instincts That Make Us Overeat. It was a labor of love. I really feel quite fortunate to have been able to be the person to write this book. It incorporated some of my own research, but really it’s mostly the research of many other people in the scientific community who I think have done great work and that I really respect. And it covers researchers from fields of neuroscience, and anthropology, and psychology, and other fields. And I think it’s a really cool cross-section for understanding how we eat and gain, how we overeat and gain excess fat. And that’s available from pretty much anywhere where you would normally buy books.
Also, Red Pen Reviews. Reviews are available for free on redpenreviews.org. We are a registered charity in Washington state, so we’re not out to make money. We’re actually struggling a bit financially. So if you want to donate a bit to help us do what we do, that’d be much appreciated. But check it out because the cool thing about our pages is you can land on them and engage with it to any depth you want. So literally within two seconds, you can see the title of the book and the overall numerical score we gave it. Just like Rotten Tomatoes, you can just land the page and boom, you have some idea of what the book is about. Then you can look at the scores if you want to spend a few more seconds. You can read the summary if you want to spend one or two minutes understanding why we rated it like it is and what the book’s about and stuff. And then below that, we have the full review where we justify every single score that we gave that book, and we have an extensive review of the science and the book itself. So we’re completely transparent.
DrMR: That’s amazing by the way. I can’t wait to look at this myself.
DrSG: I appreciate that. Yeah. Our process is completely transparent. It’s on the website. You can see exactly how we review these books. As far as I’m aware, there is no other process like it. There’s nowhere else where you can get this type of health and nutrition book review that is so structured and rigorous, and administered by subject-specific experts. It takes us a lot of time to produce these, but we’re really hoping that this is going to not only change the public’s access to high-quality information about popular health and nutrition books, but ultimately reshape the landscape of health and nutrition publishing, making it care more about information accuracy really is what we’re looking for.
DrMR: I would really encourage our audience if you go over there and if you benefit in any way, I would highly encourage you to donate. I’m actually going to go over there and donate in a minute or two myself because operations like this we need to support. The market is going to give us more of what we support financially. So it’s just so vitally important that if you find value in someone’s work, financially support it. I think sometimes we assume just because there’s a nice-looking website and what looks like a well-performed analysis there, that they’re automatically turning a profit. And oftentimes, that’s not the case. And financial support from people is crucial. I’m going to go over there and donate momentarily because you’ve already sold me. I think that is fantastic. In fact, I think I didn’t realize this was you when I came across your review of The China Study book.
DrMR: I found that fantastic. So audience, I would if you can, I would go over and support the work because I wholeheartedly believe we need more of this.
DrSG: Well, thank you. I appreciate that.
DrMR: Yeah, absolutely. Well Stephan, thanks again for taking the time. This has been a great conversation. And I really appreciate all the good work that you’re doing.
DrSG: Yeah, my pleasure. Thank you.