There have been a few posts about the obesity crisis here, and I’m honestly a bit confused about some theories that people are passing around. I’m one of those people thinks that the “calories in, calories” (CICO) theory is largely correct, relevant, and helpful for explaining our current crisis.
I’m not actually sure to what extent people here disagree with my basic premises, or whether they just think I’m missing a point. So let me be more clear.
As I understand, there are roughly three critiques you can have against the CICO theory. You can think it’s,
(1) largely incorrect (2) largely irrelevant (3) largely just smugness masquerading as a theory
I think that (1) is simply factually wrong. In order for the calorie intake minus expenditure theory to be factually incorrect, scientists would need to be wrong about not only minor details, but the basic picture concerning how our metabolism works. Therefore, I assume that the real meat of the debate is in (2) and (3).
Yet, I don’t see how (2) and (3) are defensible either. As a theory, CICO does what it needs to do: compellingly explains our observations. It provides an answer to the question, “Why are people obese at higher rates than before?”, namely, “They are eating more calories than before, or expending fewer calories, or both.”
I fully admit that CICO doesn’t provide an explanation for why we eat more calories before, but it never needed to on its own. Theories don’t need to explain everything to be useful. And I don’t think many credible people are claiming that “calories in, calories out” was supposed to provide a complete picture of what’s happening (theories rarely explain what drives changes to inputs in the theory). Instead, it merely clarifies the mechanism of why we’re in the current situation, and that’s always important.
It’s also not about moral smugness, any more than any other epistemic theory. The theory that quitting smoking improves one’s health does not imply that people who don’t quit are unvirtuous, or that the speaker is automatically assuming that you simply lack willpower. Why? Because is and ought are two separate things.
CICO is about how obesity comes about. It’s not about who to blame. It’s not about shaming people for not having willpower. It’s not about saying that you have sinned. It’s not about saying that we ought to individually voluntarily reduce our consumption. For crying out loud, it’s an epistemic theory not a moral one!
To state the obvious, without clarifying the basic mechanism of how a phenomenon works in the world, you’ll just remain needlessly confused.
Imagine if people all around the world people were getting richer (as measured in net worth), and we didn’t know why. To be more specific, suppose we didn’t understand the “income minus expenses” theory of wealth, so instead we went around saying things like, “it could be the guns”, “it could be factories”, “it could be the that we have more computers.” Now, of course, all of these explanations could play a role in why we’re getting richer over time, but none of them make any sense without connecting them to the “income minus expenses theory.”
To state “wealth is income minus expenses” does not in any way mean that you are denying how guns, factories, and computers might play a role in wealth accumulation. It simply focuses the discussion on ways that those things could act through the basic mechanism of how wealth operates.
If your audience already understands that this is how wealth works, then sure, you don’t need to mention it. But in the case of the obesity debate, there are a ton of people who don’t actually believe in CICO; in other words, there are a considerable number of people who firmly believe critique (1). Therefore, refusing to clarify how your proposed explanation connects to calories, in my opinion, generates a lot of unnecessary confusion.
As usual, the territory is never mysterious. There are only brains who are confused. If you are perpetually confused by a phenomenon, that is a fact about you, and not the phenomenon. There does not in fact need to be a complicated, clever mechanism that explains obesity that all researchers have thus far missed. It could simply be that the current consensus is correct, and we’re eating too many calories. The right question to ask is what we can do to address that.
How it seems to be typically used, literal CICO as an observation is the motte, and the corresponding bailey is something like: “yes, it is simple to lose weight, you just need to stop eating all those cakes and start exercising, but this is the truth you don’t want to hear so you keep making excuses instead”.
How do you feel about the following theory: “atoms in, atoms out”? I mean, this one should be scientifically even less controversial. So why do you prefer the version with calories over the version with atoms? From the perspective of “I am just saying it, because it is factually true, there is no judgment or whatever involved”, both theories are equal. What specifically is the advantage of the version with calories?
(My guess is that the obvious problem with the “atoms in, atoms out” theory is that the only actionable advice it hints towards is to poop more, or perhaps exhale more CO2… but the obvious problem with such advice is that the fat people do not have conscious control over extracting fat from their fat cells and converting it to waste. Otherwise, many would willingly convert and poop it out in one afternoon and have their problem solved. Well, guess what, the “calories in, calories out” has exactly the same problem, only in less obvious form: if your metabolism decides that it is not going to extract fat from your fat cells and convert it to useful energy which could be burned in muscles, there is little you can consciously do about it; you will spend the energy outside of your fat cells, then you are out of useful energy, end of story, some guy on internet unhelpfully reminding you that you didn’t spend enough calories.)
What specifically is the advantage of the version with calories?
Well, let me consider a recent, highly upvoted post on here: A Contamination Theory of the Obesity Epidemic. In it, the author says that the explanation for the obesity crisis can’t be CICO,
“It’s from overeating!”, they cry. But controlled overfeeding studies (from the 1970′s—pre-explosion) struggle to make people gain weight and they loose it quickly once the overfeeding stops. (Which is evidence against a hysteresis theory.)
“It’s lack of exercise”, they yell. But making people exercise doesn’t seem to produce significant weight loss, and obesity is still spreading despite lots of money and effort being put into exercise.
If CICO is literally true, in the same way that the “atoms in, atoms out” theory is true, then this debunking is very weak. The obesity epidemic must be due to either overeating or lack of exercise, or both.
The real debate is, of course, over which environmental factors caused us to eat more, or exercise less. But if you don’t even recognize that the cause must act through this mechanism, then you’re not going to get very far in your explanation. That’s how you end up proposing that it must be some hidden environmental factor, as this post does, rather than more relevant things related to the modern diet.
My own view is that the most likely cause of our current crisis is that modern folk have access to more and a greater variety of addicting processed food, so we end up consistently overeating. I don’t think this theory is obviously correct, and of course it could be wrong. However, in light of the true mechanism behind obesity, it makes a lot more sense to me than many other theories that people have proposed, especially any that deny we’re overeating from the outset.
Well, here is the point where we disagree. My opinion is that CICO, despite being technically true, focuses your attention on eating and exercise as the most relevant causes of obesity. I agree with the statement “calories in = calories out” as observation. I disagree with the conclusion that the most relevant things for obesity are how much you eat and how much you exercise. And my aversion against CICO is that it predictably leads people to this conclusion. As you have demonstrated right now.
I am not an expert, but here are a few questions that I think need to be answered in order to get a “gears model” of obesity. See how none of them contradicts CICO, but they all cast doubt on the simplistic advice to “just eat less and exercise more”.
when you put food in your mouth, what mechanism decides which nutrients enter the bloodstream and which merely pass the digestive system and get out of the body?
when the nutrient are in the blodstream, what mechanism decides which of them are used to build/repair cells, which are stored as energy sources in muscles, and which are stored as energy reserves in fat cells?
when the energy reserves are in the fat cells, what mechanism decides whether they get released into the bloodstream again?
(probably some more important questions I forgot now)
When people talk about “metabolic privilege”, they roughly mean that some people are lucky that for some reason, even if they eat a lot, it does not result in storing fat in fat cells. I am not sure what exactly happens instead; whether the nutrients get expelled from the body, or whether the metabolism stubbornly stores them in muscles and refuses to store them in the fat cells, so that the person feels full of energy all day long. Those people can overeat as much as they can, and yet they don’t get weight.
Then you have the opposite type of people, whose metabolism stubbornly refuses to release the fat from fat cells, no matter how much they starve or how much they try to exercise. Eating just slightly more than appropriate results immediately in weight gain. (In extreme cases, if they try to starve, they will just get weak and maybe fall in coma, but they still won’t lose a single kilogram.)
The obvious question is what separates these two groups of people, and what can be done if you happen to be in the latter? The simplistic response “calories in, calories out” provides absolutely no answer to this, it is just a smug way to avoid the question and pretend that it does not matter.
Sometimes this changes with age. In my 20s, I could eat as much as I wanted, and I barely ever exercised, yet my body somehow handled the situation without getting much overweight. In my 40s, I can do cardio and weightlifting every day, and barely eat anything other than fresh vegetables, and the weight only goes down at a microscopic speed, and if I ever eat a big lunch again (not a cake, just a normal lunch) the weight immediately jumps back. The “calories in, calories out” model neither predicts this, nor offers a solution. It doesn’t even predict that when I try some new diet, sometimes I lose a bit weight during the first week, but then I get it back the next week, despite doing the same thing both weeks. I do eat less and exercise more than I did in the past, yet I keep gaining weight.
Now, this is generally known that age makes weight loss way more difficult. But the specific mechanism is something more than just eating more and exercising less, because it happens even if you eat less and exercise more. And if this works differently for the same person at a different age, it seems plausible that it can also work differently for two different people at the same age. In the search for the specific mechanism, the answer “calories in, calories out” is an active distraction.
To clarify, there are two related but separate questions about obesity that are worth distinguishing,
What explains why people are more obese than 50 years ago? And what can we do about it?
What explains why some people are more obese than others, at a given point of time? And what can we do about it?
In my argument, I was primarily saying that CICO was important for explaining (1). For instance, I do not think that the concept of metabolic privilege can explain much of (1), since 50 years is far too little of time for our metabolisms to evolve in such a rapid and widespread manner. So, from that perspective, I really do think that overconsumption and/or lack of exercise are the important and relevant mechanisms driving our current crisis. And further, I think that our overconsumption is probably related to processed food.
I did not say much about (2), but I can say a little about my thoughts now. I agree that people vary in how “fast” their metabolisms expend calories. The most obvious variation is, as you mentioned, the difference between the youthful metabolism and the metabolism found in older people.
However...
Then you have the opposite type of people, whose metabolism stubbornly refuses to release the fat from fat cells, no matter how much they starve or how much they try to exercise… (In extreme cases, if they try to starve, they will just get weak and maybe fall in coma, but they still won’t lose a single kilogram.)
I don’t think these people are common, at least in a literal sense. Obesity is very uncommon in pre-industrialized cultures, and in hunter-gatherer settings. I think this is very strong evidence that it is feasible for the vast majority of people to be non-obese under the right environmental circumstances (though feasible does not mean easy, or that it can be done voluntarily in our current world). I also don’t find personal anecdotes from people about the intractability of losing weight compelling, given this strong evidence.
Furthermore, in addition to the role of metabolism, I would also point to the role of cognitive factors like delayed gratification in explaining obesity. You can say that this is me just being “smug” or “blaming fat people for their own problems” but this would be an overly moral interpretation of what I view as simply an honest causal explanation. A utilitarian might say that we should only blame people for things that they have voluntary control over. So in light of the fact that cognitive abilities are largely outside of our control, I would never blame an obese person for their own condition.
Instead of being moralistic, I am trying to be honest. And being honest about the cause of a phenomenon allows us to invent better solutions than the ones that exist. Indeed, if weight loss is a simple matter of overconsumption, and we also admit that people often suffer from problems of delayed gratification, then I think this naturally leads us to propose medical interventions like bariatric surgery or weight loss medication—both of which have a much higher chance of working than solutions rooted in a misunderstanding of the real issue.
Just shortly, because I am really not an expert on this, so debating longly feels inappropriate (it feels like suggesting that I know more than I actually do).
What explains why people are more obese than 50 years ago?
I still feel like there are at least two explanations here. Maybe it is more food and less hard work, in general. Or maybe it is something in the food that screws up many (but not all) people’s metabolism.
Like, maybe some food additive that we use because it improves the taste, also has an unknown side effect of telling people’s bodies to prioritize storing energy in fat cells over delivering it to muscles. And if the food additive is only added to some type of foods, or affects only people with certain genes, that might hypothetically explain why some people get fat and some don’t.
Now, I am probably not the first person to think about this—if it is about lifestyle, then perhaps we should see clear connection between obesity and profession. To put it bluntly, are people working in offices more fat than people doing hard physical work? I admit I never actually paid attention to this.
Maybe it is more food and less hard work, in general. Or maybe it is something in the food that screws up many (but not all) people’s metabolism.
I’m with you that it probably has to do with what’s in our food. Unlike some, however, I’m skeptical that we can nail it down to “one thing”, like a simple additive, or ingredient. It seems most likely to me that companies have simply done a very good job optimizing processed food to be addicting, in the last 50 years. That’s their job, anyway.
Now, I am probably not the first person to think about this—if it is about lifestyle, then perhaps we should see clear connection between obesity and profession. To put it bluntly, are people working in offices more fat than people doing hard physical work? I admit I never actually paid attention to this.
That’s a good question. I haven’t looked into this, and may soon. My guess is that you’d probably have to adjust for cognitive confounders, but after doing so I’d predict that people in highly physically demanding professions tend to be thinner and more fit (in the sense of body fat percentage, not necessarily BMI). However, I’d also suspect that the causality may run in the reverse direction; it’s a lot easier to exercise if you’re thin.
There are viruses that get people to gain weight. They might do that by getting people to eat more. They might also do that by getting people to burn less calories.
The hypothesis that viruses are responsible for the obesity epidemic is a possible one. If it would be the main cause literal CICO or Mass-In-Mass-out would still be correct but not very useful when thinking about how to combat the epidemic.
The virus hypothesis has for example the advantage that it explains why the lab animals with controlled diets also gained weight and not just the humans who have a free choice about what to eat in a world with more processed food.
Overeating due to addicting processed food also doesn’t explain why people fail so often at diets and regain their weight. In that model it would be easier to lose weight longterm by avoiding processed food.
The obesity epidemic must be due to either overeating or lack of exercise, or both.
No, the healthy body has plenty of different ways to burn calories then exercise and is willing to use them to stay at a constant weight.
A lot of processes in the body are cybernetic in nature. There’s a target value and then the body tries to maintain that target. The body both has indirect ways to maintain the target by setting hunger, adrenalin or up/down-regulate a variety of metabolic processes.
Herman Pontzer work about how exercising more often doesn’t result in net calorie burn because the body downregulates metabolic processes to safe energy.
Calorie-in-calorie-out also isn’t great at explaining the weight gain in lab animals with a controlled diet.
To state “wealth is income minus expenses” does not in any way mean that you are denying how guns, factories, and computers might play a role in wealth accumulation.
That model doesn’t explain why Jeff Bezos or Elon Musk are so rich because both have very little income compared to the wealth they have.
On the one hand, CICO is obviously true, and any explanation of obesity that doesn’t contain CICO somewhere is missing an important dynamic.
But the reason why I think CICO is getting grilled so much lately, is that it’s far from the most important piece of the puzzle, and people often cite CICO as if it were the main factor. Biological and psychological explanations for why CI > CO at healthy BMIs (thereby leading BMI to increase until it becomes unhealthy) are more important than simply observing that weight will increase when CI > CO. Note that this can be formulated without any reference to CICO, although I used a formulation here that did use CICO.
There have been a few posts about the obesity crisis here, and I’m honestly a bit confused about some theories that people are passing around. I’m one of those people thinks that the “calories in, calories” (CICO) theory is largely correct, relevant, and helpful for explaining our current crisis.
I’m not actually sure to what extent people here disagree with my basic premises, or whether they just think I’m missing a point. So let me be more clear.
As I understand, there are roughly three critiques you can have against the CICO theory. You can think it’s,
(1) largely incorrect
(2) largely irrelevant
(3) largely just smugness masquerading as a theory
I think that (1) is simply factually wrong. In order for the calorie intake minus expenditure theory to be factually incorrect, scientists would need to be wrong about not only minor details, but the basic picture concerning how our metabolism works. Therefore, I assume that the real meat of the debate is in (2) and (3).
Yet, I don’t see how (2) and (3) are defensible either. As a theory, CICO does what it needs to do: compellingly explains our observations. It provides an answer to the question, “Why are people obese at higher rates than before?”, namely, “They are eating more calories than before, or expending fewer calories, or both.”
I fully admit that CICO doesn’t provide an explanation for why we eat more calories before, but it never needed to on its own. Theories don’t need to explain everything to be useful. And I don’t think many credible people are claiming that “calories in, calories out” was supposed to provide a complete picture of what’s happening (theories rarely explain what drives changes to inputs in the theory). Instead, it merely clarifies the mechanism of why we’re in the current situation, and that’s always important.
It’s also not about moral smugness, any more than any other epistemic theory. The theory that quitting smoking improves one’s health does not imply that people who don’t quit are unvirtuous, or that the speaker is automatically assuming that you simply lack willpower. Why? Because is and ought are two separate things.
CICO is about how obesity comes about. It’s not about who to blame. It’s not about shaming people for not having willpower. It’s not about saying that you have sinned. It’s not about saying that we ought to individually voluntarily reduce our consumption. For crying out loud, it’s an epistemic theory not a moral one!
To state the obvious, without clarifying the basic mechanism of how a phenomenon works in the world, you’ll just remain needlessly confused.
Imagine if people all around the world people were getting richer (as measured in net worth), and we didn’t know why. To be more specific, suppose we didn’t understand the “income minus expenses” theory of wealth, so instead we went around saying things like, “it could be the guns”, “it could be factories”, “it could be the that we have more computers.” Now, of course, all of these explanations could play a role in why we’re getting richer over time, but none of them make any sense without connecting them to the “income minus expenses theory.”
To state “wealth is income minus expenses” does not in any way mean that you are denying how guns, factories, and computers might play a role in wealth accumulation. It simply focuses the discussion on ways that those things could act through the basic mechanism of how wealth operates.
If your audience already understands that this is how wealth works, then sure, you don’t need to mention it. But in the case of the obesity debate, there are a ton of people who don’t actually believe in CICO; in other words, there are a considerable number of people who firmly believe critique (1). Therefore, refusing to clarify how your proposed explanation connects to calories, in my opinion, generates a lot of unnecessary confusion.
As usual, the territory is never mysterious. There are only brains who are confused. If you are perpetually confused by a phenomenon, that is a fact about you, and not the phenomenon. There does not in fact need to be a complicated, clever mechanism that explains obesity that all researchers have thus far missed. It could simply be that the current consensus is correct, and we’re eating too many calories. The right question to ask is what we can do to address that.
How it seems to be typically used, literal CICO as an observation is the motte, and the corresponding bailey is something like: “yes, it is simple to lose weight, you just need to stop eating all those cakes and start exercising, but this is the truth you don’t want to hear so you keep making excuses instead”.
How do you feel about the following theory: “atoms in, atoms out”? I mean, this one should be scientifically even less controversial. So why do you prefer the version with calories over the version with atoms? From the perspective of “I am just saying it, because it is factually true, there is no judgment or whatever involved”, both theories are equal. What specifically is the advantage of the version with calories?
(My guess is that the obvious problem with the “atoms in, atoms out” theory is that the only actionable advice it hints towards is to poop more, or perhaps exhale more CO2… but the obvious problem with such advice is that the fat people do not have conscious control over extracting fat from their fat cells and converting it to waste. Otherwise, many would willingly convert and poop it out in one afternoon and have their problem solved. Well, guess what, the “calories in, calories out” has exactly the same problem, only in less obvious form: if your metabolism decides that it is not going to extract fat from your fat cells and convert it to useful energy which could be burned in muscles, there is little you can consciously do about it; you will spend the energy outside of your fat cells, then you are out of useful energy, end of story, some guy on internet unhelpfully reminding you that you didn’t spend enough calories.)
Well, let me consider a recent, highly upvoted post on here: A Contamination Theory of the Obesity Epidemic. In it, the author says that the explanation for the obesity crisis can’t be CICO,
If CICO is literally true, in the same way that the “atoms in, atoms out” theory is true, then this debunking is very weak. The obesity epidemic must be due to either overeating or lack of exercise, or both.
The real debate is, of course, over which environmental factors caused us to eat more, or exercise less. But if you don’t even recognize that the cause must act through this mechanism, then you’re not going to get very far in your explanation. That’s how you end up proposing that it must be some hidden environmental factor, as this post does, rather than more relevant things related to the modern diet.
My own view is that the most likely cause of our current crisis is that modern folk have access to more and a greater variety of addicting processed food, so we end up consistently overeating. I don’t think this theory is obviously correct, and of course it could be wrong. However, in light of the true mechanism behind obesity, it makes a lot more sense to me than many other theories that people have proposed, especially any that deny we’re overeating from the outset.
Well, here is the point where we disagree. My opinion is that CICO, despite being technically true, focuses your attention on eating and exercise as the most relevant causes of obesity. I agree with the statement “calories in = calories out” as observation. I disagree with the conclusion that the most relevant things for obesity are how much you eat and how much you exercise. And my aversion against CICO is that it predictably leads people to this conclusion. As you have demonstrated right now.
I am not an expert, but here are a few questions that I think need to be answered in order to get a “gears model” of obesity. See how none of them contradicts CICO, but they all cast doubt on the simplistic advice to “just eat less and exercise more”.
when you put food in your mouth, what mechanism decides which nutrients enter the bloodstream and which merely pass the digestive system and get out of the body?
when the nutrient are in the blodstream, what mechanism decides which of them are used to build/repair cells, which are stored as energy sources in muscles, and which are stored as energy reserves in fat cells?
when the energy reserves are in the fat cells, what mechanism decides whether they get released into the bloodstream again?
(probably some more important questions I forgot now)
When people talk about “metabolic privilege”, they roughly mean that some people are lucky that for some reason, even if they eat a lot, it does not result in storing fat in fat cells. I am not sure what exactly happens instead; whether the nutrients get expelled from the body, or whether the metabolism stubbornly stores them in muscles and refuses to store them in the fat cells, so that the person feels full of energy all day long. Those people can overeat as much as they can, and yet they don’t get weight.
Then you have the opposite type of people, whose metabolism stubbornly refuses to release the fat from fat cells, no matter how much they starve or how much they try to exercise. Eating just slightly more than appropriate results immediately in weight gain. (In extreme cases, if they try to starve, they will just get weak and maybe fall in coma, but they still won’t lose a single kilogram.)
The obvious question is what separates these two groups of people, and what can be done if you happen to be in the latter? The simplistic response “calories in, calories out” provides absolutely no answer to this, it is just a smug way to avoid the question and pretend that it does not matter.
Sometimes this changes with age. In my 20s, I could eat as much as I wanted, and I barely ever exercised, yet my body somehow handled the situation without getting much overweight. In my 40s, I can do cardio and weightlifting every day, and barely eat anything other than fresh vegetables, and the weight only goes down at a microscopic speed, and if I ever eat a big lunch again (not a cake, just a normal lunch) the weight immediately jumps back. The “calories in, calories out” model neither predicts this, nor offers a solution. It doesn’t even predict that when I try some new diet, sometimes I lose a bit weight during the first week, but then I get it back the next week, despite doing the same thing both weeks. I do eat less and exercise more than I did in the past, yet I keep gaining weight.
Now, this is generally known that age makes weight loss way more difficult. But the specific mechanism is something more than just eating more and exercising less, because it happens even if you eat less and exercise more. And if this works differently for the same person at a different age, it seems plausible that it can also work differently for two different people at the same age. In the search for the specific mechanism, the answer “calories in, calories out” is an active distraction.
To clarify, there are two related but separate questions about obesity that are worth distinguishing,
What explains why people are more obese than 50 years ago? And what can we do about it?
What explains why some people are more obese than others, at a given point of time? And what can we do about it?
In my argument, I was primarily saying that CICO was important for explaining (1). For instance, I do not think that the concept of metabolic privilege can explain much of (1), since 50 years is far too little of time for our metabolisms to evolve in such a rapid and widespread manner. So, from that perspective, I really do think that overconsumption and/or lack of exercise are the important and relevant mechanisms driving our current crisis. And further, I think that our overconsumption is probably related to processed food.
I did not say much about (2), but I can say a little about my thoughts now. I agree that people vary in how “fast” their metabolisms expend calories. The most obvious variation is, as you mentioned, the difference between the youthful metabolism and the metabolism found in older people.
However...
I don’t think these people are common, at least in a literal sense. Obesity is very uncommon in pre-industrialized cultures, and in hunter-gatherer settings. I think this is very strong evidence that it is feasible for the vast majority of people to be non-obese under the right environmental circumstances (though feasible does not mean easy, or that it can be done voluntarily in our current world). I also don’t find personal anecdotes from people about the intractability of losing weight compelling, given this strong evidence.
Furthermore, in addition to the role of metabolism, I would also point to the role of cognitive factors like delayed gratification in explaining obesity. You can say that this is me just being “smug” or “blaming fat people for their own problems” but this would be an overly moral interpretation of what I view as simply an honest causal explanation. A utilitarian might say that we should only blame people for things that they have voluntary control over. So in light of the fact that cognitive abilities are largely outside of our control, I would never blame an obese person for their own condition.
Instead of being moralistic, I am trying to be honest. And being honest about the cause of a phenomenon allows us to invent better solutions than the ones that exist. Indeed, if weight loss is a simple matter of overconsumption, and we also admit that people often suffer from problems of delayed gratification, then I think this naturally leads us to propose medical interventions like bariatric surgery or weight loss medication—both of which have a much higher chance of working than solutions rooted in a misunderstanding of the real issue.
Just shortly, because I am really not an expert on this, so debating longly feels inappropriate (it feels like suggesting that I know more than I actually do).
I still feel like there are at least two explanations here. Maybe it is more food and less hard work, in general. Or maybe it is something in the food that screws up many (but not all) people’s metabolism.
Like, maybe some food additive that we use because it improves the taste, also has an unknown side effect of telling people’s bodies to prioritize storing energy in fat cells over delivering it to muscles. And if the food additive is only added to some type of foods, or affects only people with certain genes, that might hypothetically explain why some people get fat and some don’t.
Now, I am probably not the first person to think about this—if it is about lifestyle, then perhaps we should see clear connection between obesity and profession. To put it bluntly, are people working in offices more fat than people doing hard physical work? I admit I never actually paid attention to this.
I’m with you that it probably has to do with what’s in our food. Unlike some, however, I’m skeptical that we can nail it down to “one thing”, like a simple additive, or ingredient. It seems most likely to me that companies have simply done a very good job optimizing processed food to be addicting, in the last 50 years. That’s their job, anyway.
Scott Alexander reviewed a book from Stephan Guyenet about this hypothesis, and I find it quite compelling.
That’s a good question. I haven’t looked into this, and may soon. My guess is that you’d probably have to adjust for cognitive confounders, but after doing so I’d predict that people in highly physically demanding professions tend to be thinner and more fit (in the sense of body fat percentage, not necessarily BMI). However, I’d also suspect that the causality may run in the reverse direction; it’s a lot easier to exercise if you’re thin.
There are viruses that get people to gain weight. They might do that by getting people to eat more. They might also do that by getting people to burn less calories.
The hypothesis that viruses are responsible for the obesity epidemic is a possible one. If it would be the main cause literal CICO or Mass-In-Mass-out would still be correct but not very useful when thinking about how to combat the epidemic.
The virus hypothesis has for example the advantage that it explains why the lab animals with controlled diets also gained weight and not just the humans who have a free choice about what to eat in a world with more processed food.
Overeating due to addicting processed food also doesn’t explain why people fail so often at diets and regain their weight. In that model it would be easier to lose weight longterm by avoiding processed food.
No, the healthy body has plenty of different ways to burn calories then exercise and is willing to use them to stay at a constant weight.
A lot of processes in the body are cybernetic in nature. There’s a target value and then the body tries to maintain that target. The body both has indirect ways to maintain the target by setting hunger, adrenalin or up/down-regulate a variety of metabolic processes.
Herman Pontzer work about how exercising more often doesn’t result in net calorie burn because the body downregulates metabolic processes to safe energy.
Calorie-in-calorie-out also isn’t great at explaining the weight gain in lab animals with a controlled diet.
That model doesn’t explain why Jeff Bezos or Elon Musk are so rich because both have very little income compared to the wealth they have.
On the one hand, CICO is obviously true, and any explanation of obesity that doesn’t contain CICO somewhere is missing an important dynamic.
But the reason why I think CICO is getting grilled so much lately, is that it’s far from the most important piece of the puzzle, and people often cite CICO as if it were the main factor. Biological and psychological explanations for why CI > CO at healthy BMIs (thereby leading BMI to increase until it becomes unhealthy) are more important than simply observing that weight will increase when CI > CO. Note that this can be formulated without any reference to CICO, although I used a formulation here that did use CICO.