I found my way here, finally, from ACX Open Thread 353. There, last October, I was skeptical whether we really *know* that exercise benefits health. Could this all be bullsh*t, like perhaps the standard praise for fruit and vegetables? Now I finally found the time to follow it up (a bit). In that ACX comment thread, you linked to your review of Lieberman's book here. And to me specifically you quoted the following passage from the book (also part of the review here):
> "In every study, the largest benefit came from just ninety weekly minutes of exercise, yielding an average 20 percent reduction in the risk of dying. After that, the risk of death drops with increasing doses but less steeply."
So I looked that up now, the referenced paper Wasfy & Baggish 2016, and it turns out the studies he refers to in this passage are all observational only. "To date, there have been no randomized controlled trials designed to examine the impact of PA [physical activity] on mortality." And yet Lieberman writes "came from", and such language is standard for that section in his book, a section which shows no awareness that higher mortality and physical inactivity could easily be both caused by a third factor. That's enough to undermine my trust in his theories. If he discusses the issue elsewhere in the book, your review doesn't mention it.
Speaking of the review, I found the style different, for better or worse, from that of, say, an ACX review. It doesn't seem like an open-ended investigation. In particular, take this passage:
> "Sitting slows the rate we take up fats and sugars in the bloodstream, and whatever isn't taken up will turn into fat. Sitting is usually accompanied by psychosocial stress, and that stress increases cortisol and makes you pack on organ fat. Another way it increases inflammation is [...]"
The point about stress is a confounder! Perhaps it's, not actually the physical non-activity of sitting, but the stress (associated with it for other reasons) that impairs health? That should have gone on the other side of the ledger! But you just pile everything on one side, on the pro-exercise side, and that's true for most of the post.
Meanwhile, the Morris studies you invoked in the ACX thread aren't quite as convincing as I first thought, since presumably people partly self-selected into the different jobs, such as bus driver vs ticket taker, depending to how comfortable their bodies feel with PA.
Of the evidence presented for the health benefits of PA, I find the Danish two-weeks study most convincing. You invoked it to me in the ACX thread (and you also note it here in the Lieberman review), so thanks again for that.
And I should make it clear that in that thread you recommended your Lieberman review to someone else. Not to me, the skeptic, whom a more open-ended investigation would have suited better. Finally, let me also say that I found the writing here good and entertaining --- I'm not surprised that the Substack has been catching on quickly. On this older post I'm the only commenter (as of now) but on newer ones such privilege would be very unusual.
> The point about stress is a confounder! Perhaps it's, not actually the physical non-activity of sitting, but the stress (associated with it for other reasons) that impairs health? That should have gone on the other side of the ledger! But you just pile everything on one side, on the pro-exercise side, and that's true for most of the post.
Yeah, I think overall, this was much more an "advocacy" piece from my end than an "adversarial" piece, and you seem to have a pretty strict evidentiary standard when it comes to exercise in particular.
To your stress point, it's confounded with a lot of other things - inactivity and genetics, diet, probably smoking, and who knows what else, and bad habits and "bad" genetics usually cluster together. There's also decent evidence that exercise helps lower stress and anxiety and improves mental health, it's generally as big an effect size as antidepressants and therapy, so you're confounded there as well.
Especially for things like exercise and physical health, which are multi-factorial and massively confounded with things like your existing healthiness, diet, stress, and genetics, even RCT's are noisy, and the endpoints we care most about are far off and rare events (like all cause mortality, or morbidity), RCT's generally can't run long enough to show statistically valid effects, and would be too expensive to do, and wouldn't ever actually control for everything that was impacting the endpoints.
I can think of RCT's where people were randomly assigned exercise of various amounts, up to and including large amounts, but who didn't show weight loss because of increased calorie consumption, and they would likely also have shown less of a lift in health status overall than people who didn't increase their calories and showed weight loss.
I can think of diet RCT's where people were taken into a study center and had their diets completely controlled, and lost significant weight and had better health metrics.
I can think of studies where "responsiveness" to exercise were measured, with ~20% differences in incremental changes in VO2max, blood pressure, and cholesterol effects on either end, too, so there's innate genetic variance.
Ultimately, even if you RCT'd people into a study for months with diet and exercise controlled, you're not going to be controlling for everything. Their stress and daily lives will be way different, their exposure to pollutants, and more.
I think at some point, obvervational is the best you can do, and I think the evidence is pretty abundant that physical activity overall is protective for basically every negative outcome, up to and including all cause mortality.
Maybe those people have better diets and less stress as well? Sure. So optimize your diet and stress too, absolutely.
Ultimately, what you actually want for yourself is less morbidity, better health, more energy and joie de vivre, and lower all cause mortality, right? Exercise is a part of that, and so is diet, and so is stress, and so is genetics. You can't do much about genetics, but you can move the needle on all the other things.
I'd be interested if you feel the same about ultra processed food - I came in as a skeptic on that one, and became convinced that it's actually bad on further research.
Maybe we should do an adversarial collaboration if Scott does another one of those? Could be fun and interesting. :-)
Thank you for the detailed response! In the stress confounder, I'm not invested; I just found that passage in your post the best one to illustrate that it was more of an "advocacy" piece as you call it now. And again, this is fair enough, I'm not saying self-aware advocacy is bad.
What about ultra-processed food? I see you have posts on that, these would be my entry point if I find more time for these topics (but it would probably take months again). My default here is strong skepticism, it's like people think of "processing" the food as casting a bad magical spell over it (I think Scott may have written something like that).
My own favourite theory, but without full confidence, of Western diseases is poisoning by sugar and refined carbohydrates, i.e. Gary Taubes (and others). That theory predicts that people become chronically hungry and tired, and develop health problems. Thus it predicts an association between physical inactivity and mortality which is *not* causal. On the other hand, even Taubes does not dispute that exercise yields health benefits, as far as I know. And the observed association is large: you say in the post that it's higher even than for smoking.
And I acknowledged already the Danish study. Overall, if I had to bet, I guess I would bet that physical activity is beneficial for health ... there goes the adversarial collaboration opportunity :-( but I seem to remember anyway that Scott was disappointed with the adversarial contest, that's why he switched to something else (the book reviews).
> My default here is strong skepticism, it's like people think of "processing" the food as casting a bad magical spell over it (I think Scott may have written something like that).
Yeah, the basic argument here is that much like apps have teams of thousands of Phd's on the other side exerting their collective brainpower to get you to glue your eyeballs to your phone more, and this has driven "hours per day on phones" from 2 hours to 7 hours per day now (the average for Americans as of 2023), ultra processed food has similar teams of Phd's trying to optimize "tastiness" and "you eating more," and they've succeeded wildly in the aggregate, just like the phone / app people.
There's also some pretty solid "totally controlled diet" studies directly contrasting "real" and "ultra processed food" diets in different orders for weeks, with quite strong results, as well as ones measuring metabolite levels in blood (the problem with most diet studies is they use surveys and memory vs actually rigorous tracking, and these methods get around that).
But yeah, if you do get around to reading my two processed food posts, interested in what you think.
> Overall, if I had to bet, I guess I would bet that physical activity is beneficial for health ... there goes the adversarial collaboration opportunity
Ah, quelle dommage. :-)
That's good though, I'm glad we're at least interpreting the evidence (confounded and observational though it may largely be) in mostly the same direction.
> My own favourite theory, but without full confidence, of Western diseases is poisoning by sugar and refined carbohydrates, i.e. Gary Taubes (and others). That theory predicts that people become chronically hungry and tired, and develop health problems.
One interesting data point here - among those training for and doing triathlons, which I'm among, there's a split between people who go really carb heavy, and those who go for more fat / protein. And the carb heavy people generally do worse, health-wise, long term. They're more prone to gut and blood sugar issues when they get older and / or retire, despite the crazy training volumes theoretically "eating" most of the sugar. No studies that I'm aware of, unfortunately, this is just observational on my own part, but I think it's pretty suggestive.
A late reply from me. Not least that observation at the end about thriatletes I found indeed very interesting --- thank you!
Also, there is one paragraph in your first reply (not the second), which belatedly makes me wonder if I misunderstand something when (following Taubes) I constantly disparage observational studies and talk of large RCTs as the gold standard.
> "Ultimately, even if you RCT'd people into a study for months with diet and exercise controlled, you're not going to be controlling for everything. Their stress and daily lives will be way different, their exposure to pollutants, and more."
Despite my "pretty strict evidentiary standard" (as you called it) it wouldn't have occurred to me to complain about confounding in RCTs: as I understood it, RCTs are the gold standard exactly because they get rid of the confounders. In the sense that any confounding is now *random*, as opposed to e.g. the possible systematic non-causal association between physical inactivity and mortality that I noted in my second comment. True, RCT researchers will control for known confounders, in order to get rid even of said randomness, why wouldn't they if they can. But even if they didn't, the confounding in RCTs should be an infinitely smaller problem than the confounding in observational studies?
As for the ultra-processed foods, it will likely be a while before I find the time to delve into your posts, but thanks for the clear explanation with the PhDs and their collective brainpower (the obvious starter question from me would then be why doesn't the body just get rid of the unhealthy excess calories if the person is tricked by the PhDs into consuming those calories).
> as I understood it, RCTs are the gold standard exactly because they get rid of the confounders
Certainly I agree that RCT's are much better than observational and survey based methods, and that part of the reason they're better is that they're controlling for more confounds with their intervention via methodology.
But when you think about topics like diet and health and weight, the endpoints are multiply confounded in ways that RCT's don't really address.
Let's consider KD Halls' (excellent) study on ultra processed foods. He actually took people into the study center for 4 weeks so he could completely control their diets to compare 2 weeks of eating UPF versus two weeks of eating "real" food - both admirable and expensive.
But the health endpoints measured, and things like weight, are a factor of LOTS of different things. Diet, naturally, and that's what we're testing - but also activity levels, exercise, smoking, stress from jobs, commutes, and family and relationship, and more.
So you've suddenly brought people into your study center for 4 weeks. Now you're controlling their diet, but all the stresses in their daily life are totally mitigated - there IS no commute or crappy bosses or fighting at home. Are they allowed to smoke in the rooms in the NIH Clinical Center Metabolic Ward? I don't know, but it seems likely that they're not allowed? Well, there goes smoking.
Physical activity is definitely different too - patients are typically either confined to their rooms or the Metabolic Ward floor overall, and at least one day a week they were confined to a sealed respiratory room that monitors air exchange and consumption to measure metabolism, so they're almost certainly moving and walking less than usual.
Moreover, each room in the Metabolic Ward has a stationary bike and treadmill, so people can keep up with their usual activity - but they're here in a much different daily routine, with a lot more free time than usual. Does exercise go up compared to their regular life? Down? Who knows! It's a total wild card. And what if they didn't have bikes and treadmills? Then anyone fit would suddenly be a lot more sedentary.
So we're still confounded on a lot of other variables that we know matter.
Still, would it be any better if they went about their usual daily lives, and we just asked them to photograph or otherwise measure whatever they ate? Not necessarily - now people would get up to the usual tricks of forgetting or not reporting snacks, under-reporting calories or weight, or even changing what they eat in noticeable ways. They may change other aspects of behavior too - the Hawthorne Effect is a real thing, where people positively change their behaviors *because* they're being studied.
So RCT's are still the best we have, but they're certainly not foolproof, especially for complex and multi-factorial things like health, diet, and exercise.
> the obvious starter question from me would then be why doesn't the body just get rid of the unhealthy excess calories
On your question here, it's pretty easy to explain, there's a huge imbalance between "calorie in" vs "calorie out" capabilities and effort.
Walking an extra mile burns ~50 calories, and running an extra mile burns only 100 calories.
It's *extremely* easy to eat 200, 300, or even 500 calories extra in snacks. 200 calories is one of those tiny packs of single serving oreos or potato chips! And that's optimistic! When people snack, they usually eat a whole sleeve, or half a big bag! Do you really see anybody go out and run for 2-3 hours after that? Because that's what it would take to actually offset those calories.
It's way, way faster and easier to take in extra calories than burn them.
Like a ghost that haunts your site I'm back once more after a while ... I see now where you were coming from when you said "you're not going to be controlling for everything" in RCTs. I think what you describe is commonly filed under "lack of ecological validity", rather than under "confounding" (the term that I used and you took up in your latest reply). But surely it can be a problem, whatever it is called, and we don't have a disagreement here I guess.
As for the notion that the body cannot get rid of excess calories, that seems intuitively almost funny to me in times of high energy prices (in Europe). Why not perform any useless back-and-forth action until the energy is burnt (isn't fidgeting a visible example of that anyway)? Or simply "store" the excess energy in the excrements rather than in fat cells? Why should storing it in fat cells be easier?
I found my way here, finally, from ACX Open Thread 353. There, last October, I was skeptical whether we really *know* that exercise benefits health. Could this all be bullsh*t, like perhaps the standard praise for fruit and vegetables? Now I finally found the time to follow it up (a bit). In that ACX comment thread, you linked to your review of Lieberman's book here. And to me specifically you quoted the following passage from the book (also part of the review here):
> "In every study, the largest benefit came from just ninety weekly minutes of exercise, yielding an average 20 percent reduction in the risk of dying. After that, the risk of death drops with increasing doses but less steeply."
So I looked that up now, the referenced paper Wasfy & Baggish 2016, and it turns out the studies he refers to in this passage are all observational only. "To date, there have been no randomized controlled trials designed to examine the impact of PA [physical activity] on mortality." And yet Lieberman writes "came from", and such language is standard for that section in his book, a section which shows no awareness that higher mortality and physical inactivity could easily be both caused by a third factor. That's enough to undermine my trust in his theories. If he discusses the issue elsewhere in the book, your review doesn't mention it.
Speaking of the review, I found the style different, for better or worse, from that of, say, an ACX review. It doesn't seem like an open-ended investigation. In particular, take this passage:
> "Sitting slows the rate we take up fats and sugars in the bloodstream, and whatever isn't taken up will turn into fat. Sitting is usually accompanied by psychosocial stress, and that stress increases cortisol and makes you pack on organ fat. Another way it increases inflammation is [...]"
The point about stress is a confounder! Perhaps it's, not actually the physical non-activity of sitting, but the stress (associated with it for other reasons) that impairs health? That should have gone on the other side of the ledger! But you just pile everything on one side, on the pro-exercise side, and that's true for most of the post.
Meanwhile, the Morris studies you invoked in the ACX thread aren't quite as convincing as I first thought, since presumably people partly self-selected into the different jobs, such as bus driver vs ticket taker, depending to how comfortable their bodies feel with PA.
Of the evidence presented for the health benefits of PA, I find the Danish two-weeks study most convincing. You invoked it to me in the ACX thread (and you also note it here in the Lieberman review), so thanks again for that.
And I should make it clear that in that thread you recommended your Lieberman review to someone else. Not to me, the skeptic, whom a more open-ended investigation would have suited better. Finally, let me also say that I found the writing here good and entertaining --- I'm not surprised that the Substack has been catching on quickly. On this older post I'm the only commenter (as of now) but on newer ones such privilege would be very unusual.
> The point about stress is a confounder! Perhaps it's, not actually the physical non-activity of sitting, but the stress (associated with it for other reasons) that impairs health? That should have gone on the other side of the ledger! But you just pile everything on one side, on the pro-exercise side, and that's true for most of the post.
Yeah, I think overall, this was much more an "advocacy" piece from my end than an "adversarial" piece, and you seem to have a pretty strict evidentiary standard when it comes to exercise in particular.
To your stress point, it's confounded with a lot of other things - inactivity and genetics, diet, probably smoking, and who knows what else, and bad habits and "bad" genetics usually cluster together. There's also decent evidence that exercise helps lower stress and anxiety and improves mental health, it's generally as big an effect size as antidepressants and therapy, so you're confounded there as well.
Especially for things like exercise and physical health, which are multi-factorial and massively confounded with things like your existing healthiness, diet, stress, and genetics, even RCT's are noisy, and the endpoints we care most about are far off and rare events (like all cause mortality, or morbidity), RCT's generally can't run long enough to show statistically valid effects, and would be too expensive to do, and wouldn't ever actually control for everything that was impacting the endpoints.
I can think of RCT's where people were randomly assigned exercise of various amounts, up to and including large amounts, but who didn't show weight loss because of increased calorie consumption, and they would likely also have shown less of a lift in health status overall than people who didn't increase their calories and showed weight loss.
I can think of diet RCT's where people were taken into a study center and had their diets completely controlled, and lost significant weight and had better health metrics.
I can think of studies where "responsiveness" to exercise were measured, with ~20% differences in incremental changes in VO2max, blood pressure, and cholesterol effects on either end, too, so there's innate genetic variance.
Ultimately, even if you RCT'd people into a study for months with diet and exercise controlled, you're not going to be controlling for everything. Their stress and daily lives will be way different, their exposure to pollutants, and more.
I think at some point, obvervational is the best you can do, and I think the evidence is pretty abundant that physical activity overall is protective for basically every negative outcome, up to and including all cause mortality.
Maybe those people have better diets and less stress as well? Sure. So optimize your diet and stress too, absolutely.
Ultimately, what you actually want for yourself is less morbidity, better health, more energy and joie de vivre, and lower all cause mortality, right? Exercise is a part of that, and so is diet, and so is stress, and so is genetics. You can't do much about genetics, but you can move the needle on all the other things.
I'd be interested if you feel the same about ultra processed food - I came in as a skeptic on that one, and became convinced that it's actually bad on further research.
Maybe we should do an adversarial collaboration if Scott does another one of those? Could be fun and interesting. :-)
Thank you for the detailed response! In the stress confounder, I'm not invested; I just found that passage in your post the best one to illustrate that it was more of an "advocacy" piece as you call it now. And again, this is fair enough, I'm not saying self-aware advocacy is bad.
What about ultra-processed food? I see you have posts on that, these would be my entry point if I find more time for these topics (but it would probably take months again). My default here is strong skepticism, it's like people think of "processing" the food as casting a bad magical spell over it (I think Scott may have written something like that).
My own favourite theory, but without full confidence, of Western diseases is poisoning by sugar and refined carbohydrates, i.e. Gary Taubes (and others). That theory predicts that people become chronically hungry and tired, and develop health problems. Thus it predicts an association between physical inactivity and mortality which is *not* causal. On the other hand, even Taubes does not dispute that exercise yields health benefits, as far as I know. And the observed association is large: you say in the post that it's higher even than for smoking.
And I acknowledged already the Danish study. Overall, if I had to bet, I guess I would bet that physical activity is beneficial for health ... there goes the adversarial collaboration opportunity :-( but I seem to remember anyway that Scott was disappointed with the adversarial contest, that's why he switched to something else (the book reviews).
> My default here is strong skepticism, it's like people think of "processing" the food as casting a bad magical spell over it (I think Scott may have written something like that).
Yeah, the basic argument here is that much like apps have teams of thousands of Phd's on the other side exerting their collective brainpower to get you to glue your eyeballs to your phone more, and this has driven "hours per day on phones" from 2 hours to 7 hours per day now (the average for Americans as of 2023), ultra processed food has similar teams of Phd's trying to optimize "tastiness" and "you eating more," and they've succeeded wildly in the aggregate, just like the phone / app people.
There's also some pretty solid "totally controlled diet" studies directly contrasting "real" and "ultra processed food" diets in different orders for weeks, with quite strong results, as well as ones measuring metabolite levels in blood (the problem with most diet studies is they use surveys and memory vs actually rigorous tracking, and these methods get around that).
But yeah, if you do get around to reading my two processed food posts, interested in what you think.
https://performativebafflement.substack.com/p/why-processed-food-makes-us-fat?r=17hw9h
https://performativebafflement.substack.com/p/processed-food-followup-ultra-processed?r=17hw9h
> Overall, if I had to bet, I guess I would bet that physical activity is beneficial for health ... there goes the adversarial collaboration opportunity
Ah, quelle dommage. :-)
That's good though, I'm glad we're at least interpreting the evidence (confounded and observational though it may largely be) in mostly the same direction.
> My own favourite theory, but without full confidence, of Western diseases is poisoning by sugar and refined carbohydrates, i.e. Gary Taubes (and others). That theory predicts that people become chronically hungry and tired, and develop health problems.
One interesting data point here - among those training for and doing triathlons, which I'm among, there's a split between people who go really carb heavy, and those who go for more fat / protein. And the carb heavy people generally do worse, health-wise, long term. They're more prone to gut and blood sugar issues when they get older and / or retire, despite the crazy training volumes theoretically "eating" most of the sugar. No studies that I'm aware of, unfortunately, this is just observational on my own part, but I think it's pretty suggestive.
A late reply from me. Not least that observation at the end about thriatletes I found indeed very interesting --- thank you!
Also, there is one paragraph in your first reply (not the second), which belatedly makes me wonder if I misunderstand something when (following Taubes) I constantly disparage observational studies and talk of large RCTs as the gold standard.
> "Ultimately, even if you RCT'd people into a study for months with diet and exercise controlled, you're not going to be controlling for everything. Their stress and daily lives will be way different, their exposure to pollutants, and more."
Despite my "pretty strict evidentiary standard" (as you called it) it wouldn't have occurred to me to complain about confounding in RCTs: as I understood it, RCTs are the gold standard exactly because they get rid of the confounders. In the sense that any confounding is now *random*, as opposed to e.g. the possible systematic non-causal association between physical inactivity and mortality that I noted in my second comment. True, RCT researchers will control for known confounders, in order to get rid even of said randomness, why wouldn't they if they can. But even if they didn't, the confounding in RCTs should be an infinitely smaller problem than the confounding in observational studies?
As for the ultra-processed foods, it will likely be a while before I find the time to delve into your posts, but thanks for the clear explanation with the PhDs and their collective brainpower (the obvious starter question from me would then be why doesn't the body just get rid of the unhealthy excess calories if the person is tricked by the PhDs into consuming those calories).
> as I understood it, RCTs are the gold standard exactly because they get rid of the confounders
Certainly I agree that RCT's are much better than observational and survey based methods, and that part of the reason they're better is that they're controlling for more confounds with their intervention via methodology.
But when you think about topics like diet and health and weight, the endpoints are multiply confounded in ways that RCT's don't really address.
Let's consider KD Halls' (excellent) study on ultra processed foods. He actually took people into the study center for 4 weeks so he could completely control their diets to compare 2 weeks of eating UPF versus two weeks of eating "real" food - both admirable and expensive.
But the health endpoints measured, and things like weight, are a factor of LOTS of different things. Diet, naturally, and that's what we're testing - but also activity levels, exercise, smoking, stress from jobs, commutes, and family and relationship, and more.
So you've suddenly brought people into your study center for 4 weeks. Now you're controlling their diet, but all the stresses in their daily life are totally mitigated - there IS no commute or crappy bosses or fighting at home. Are they allowed to smoke in the rooms in the NIH Clinical Center Metabolic Ward? I don't know, but it seems likely that they're not allowed? Well, there goes smoking.
Physical activity is definitely different too - patients are typically either confined to their rooms or the Metabolic Ward floor overall, and at least one day a week they were confined to a sealed respiratory room that monitors air exchange and consumption to measure metabolism, so they're almost certainly moving and walking less than usual.
Moreover, each room in the Metabolic Ward has a stationary bike and treadmill, so people can keep up with their usual activity - but they're here in a much different daily routine, with a lot more free time than usual. Does exercise go up compared to their regular life? Down? Who knows! It's a total wild card. And what if they didn't have bikes and treadmills? Then anyone fit would suddenly be a lot more sedentary.
So we're still confounded on a lot of other variables that we know matter.
Still, would it be any better if they went about their usual daily lives, and we just asked them to photograph or otherwise measure whatever they ate? Not necessarily - now people would get up to the usual tricks of forgetting or not reporting snacks, under-reporting calories or weight, or even changing what they eat in noticeable ways. They may change other aspects of behavior too - the Hawthorne Effect is a real thing, where people positively change their behaviors *because* they're being studied.
So RCT's are still the best we have, but they're certainly not foolproof, especially for complex and multi-factorial things like health, diet, and exercise.
> the obvious starter question from me would then be why doesn't the body just get rid of the unhealthy excess calories
On your question here, it's pretty easy to explain, there's a huge imbalance between "calorie in" vs "calorie out" capabilities and effort.
Walking an extra mile burns ~50 calories, and running an extra mile burns only 100 calories.
It's *extremely* easy to eat 200, 300, or even 500 calories extra in snacks. 200 calories is one of those tiny packs of single serving oreos or potato chips! And that's optimistic! When people snack, they usually eat a whole sleeve, or half a big bag! Do you really see anybody go out and run for 2-3 hours after that? Because that's what it would take to actually offset those calories.
It's way, way faster and easier to take in extra calories than burn them.
Like a ghost that haunts your site I'm back once more after a while ... I see now where you were coming from when you said "you're not going to be controlling for everything" in RCTs. I think what you describe is commonly filed under "lack of ecological validity", rather than under "confounding" (the term that I used and you took up in your latest reply). But surely it can be a problem, whatever it is called, and we don't have a disagreement here I guess.
As for the notion that the body cannot get rid of excess calories, that seems intuitively almost funny to me in times of high energy prices (in Europe). Why not perform any useless back-and-forth action until the energy is burnt (isn't fidgeting a visible example of that anyway)? Or simply "store" the excess energy in the excrements rather than in fat cells? Why should storing it in fat cells be easier?