Think of weight regulation as a three-layered cake :-)
The bottom layer is physics and CICO holds. The only way to lose weight is to spend more energy than you consume.
The middle layer is biochemistry. CICO still holds, but the energy output is a function of a large number of inputs (from genetic makeup to what kind of food do you eat). All the metabolic issues, insulin, leptin, ketosis, etc. live here.
The top layer is the mind. CICO still holds and all the biochemical mechanisms from the middle layer still hold, but now we add all the mental stuff—preferences, compulsions, eating-for-comfort, anorexia, eating as a displacement mechanism, etc.
And the cherry on top is that people are different. They have different metabolisms which work in different ways, they react differently to the same stimuli. No solution works for everyone and it looks likely that no solution even works for most. The only way out is to personally experiment and find out what works for you, for your personal, unique, and strange body and mind.
And we haven’t even touched the question of whether weight is the right metric to use (consider the alternatives, e.g. body fat % or general health even understood in a limited sense as absence of disease and normal metabolic markers).
The only way to lose weight is to spend more energy than you consume.
Liposuction.
The laws of thermodynamics don’t require a fat cell to release lipids because you’re hungry or exercising; the fat cells can just physically not react until your muscles run out of glucose or your brain overrules your attempt to starve yourself to death. Similarly, there’s no rule that fat cells can’t die or shrink and the waste be dumped out through urine.
Thermodynamics is not any more useful than quantum mechanics in understanding obesity. It is moralizing disguised as an invocation of natural law.
Thermodynamics is not any more useful than quantum mechanics in understanding obesity. It is moralizing disguised as an invocation of natural law.
Obesity rates used to be low. They’re now higher. The most obvious changes are higher food availability (and different food availability, read refined sugar/high fructose corn syrup/superstimuli fast food deliciousness), and more sedentary lifestyles. There may be other subtler changes, like the permanent psychological effects of being exposed to food advertising from a young age, and a million things that we don’t know yet, but there’s something out there, in the physical world, that has changed. And it’s not liposuction–that, and gastic bypass surgery, etc, didn’t exist a hundred years ago–their invention apparently hasn’t reduced obesity rates.
In summary, people moralizing about how obesity is just “calories in calories out” aren’t doing anything to solve the problem. But saying that thermodynamics is “moralizing disguised as an invocation of natural law” is just pointing out how not to solve the problem–it’s not helpful either unless you suggest an alternate solution. Or a list of 20 different things to try, at least 1 of which should work for >99.9% of the population. Or a drug that can target some mysterious fat cell receptor to make them cooperatively release energy during exercise/dieting. Or a special diet that empirically does the same thing, even if no one knows how or why. Or a way to raise children so that they have the same obesity risk as children 200 years ago. Or a way to at least treat the negative cardiovascular health benefits of obesity and make it harmless. Or liposuction. Etc etc etc. I don’t think people will get so mad about “moralizing” when this problem has a better solution.
...Oh, and a society that doesn’t massively penalize people for being chubby as long as their cardiovascular health is good would be a massive step in the right direction. As a normal weight girl who used to train in the pool every day, but still spent most of high school thinking I was fat and unattractive because of media images of models, I have a particular pet peeve with this.
The most obvious changes are higher food availability (and different food availability, read refined sugar/high fructose corn syrup/superstimuli fast food deliciousness),
In previous centuries, people rich enough not to have to worry about calories were rarely fat, certainly not at anything like modern rates. Food types have changed. Calorie supply seems like as much a red herring as the number of pirates or global warming.
Here’s someone fat enough to be a circus freak one century earlier:
“Thermodynamics” doesn’t explain that change. Some significant number of people a century ago could afford to eat as many calories as they wanted. Also, are we supposing that the circus freak was exceptionally rich?
In previous centuries, people rich enough not to have to worry about calories were rarely fat, certainly not at anything like modern rates.
This statement surprises me. I had always heard that obesity was a sign of social status, but I never thought to wonder about the actual statistics for obesity among the rich. I’m finding statements like “common among the rich,” which suggests to me that rates are probably comparable to the modern American rate, but I’m not finding numbers.
It appears that medieval monks were obese at three times the rate of the general population [src], but I’m having trouble finding the actual paper or the actual rates.
Here’s someone fat enough to be a circus freak one century earlier:
And here’s a famously fat nobleman. I read recently about Dionysius of Heraclea, who grew so fat that he could not eat, and eventually so fat that he could not breathe. (There are several other examples there of people who grew too fat to move across the centuries, including a Roman senator who was only able to walk when two slaves carried his belly for him.)
A snippet of the linked article stands out. One Michael Edelman, weighing 1200 lb at his heaviest, in the end made serious attempts to lose weight. My emphasis:
After the sudden death of Walter Hudson [another notably fat person], with whom he had formed a long-distance friendship, Michael developed a pathological fear of eating. He rapidly lost several hundred pounds, taking nourishment only when spoon fed. At about 600 lbs, he literally starved to death.
Now, it’s clear from that article that all of these people ate massive amounts, but then, one has to ask why they did that. Just what are the causal connections here? What are the causal arrows going into the “overeating” node? To say “gluttony” is just giving a name to one’s ignorance and mistaking it for knowledge. What actually distinguishes someone to whom a triple chocolate muffin with chocolate sauce and a chocolate-coated chocolate flake on top with extra chocolate is a temptation to be resisted, from someone to whom it is not a temptation?
What other arrows are going into the “obese” node? What arrows are coming out of it and where do they point?
I don’t think anyone knows the answers to these questions.
Now, it’s clear from that article that all of these people ate massive amounts, but then, one has to ask why they did that.
The first place I would look is hunger and satiety hormones. It wouldn’t surprise me if their ability to tell themselves they’re full is broken, and so they’re hungry all the time, so they eat all the time.
I had always heard that obesity was a sign of social status
I’ve heard this of Africa, but not of Europe. The reason that in preindustrial times millers were stereotypically fat is because it was assumed they pilfered a portion of the corn that farmers brought to them for milling. Friars (think of “Friar Tuck”) were stereotypically fat because they lived well (or were thought to) by visibly freeloading on the community. Neither class was well thought of for this. Being fat was taken as a sign not of status, but of idleness, sloth, greed, and gluttony.
Neither class was well thought of for this. Being fat was taken as a sign not of status, but of idleness, sloth, greed, and gluttony.
So, nobles, merchants, monks, and millers were all more likely to be fat than farmers, and all were seen by farmers as idle, greedy, gluttonous sloths. It’s not clear to me why you think that means farmers saw them as having low social status, rather than resenting their high social status.
A famously fat nobleman? LIke, that was the fat guy from the seventeenth century?
I’m not sure. My point was more than Galen knew about people so fat Jerry Springer would want to put them on his show today, and the heaviest guy you see at a sci-fi convention is comparable to the heaviest guy you would see in the Roman Senate.
I’d be way happier with “this is the percentage of monks that were obese in 1400s Britain” to compare with “this is the percentage of Americans that were obese in 2000s America.” From the qualitative descriptions I’m seeing, the rich were obese at broadly similar levels to Americans today, and I’m having trouble finding quantitative descriptions. Are you aware of data I’m not aware of?
The trouble is that routine weighing of individuals wasn’t common until industrial times, records are spotty anyway, and so we’re forced to look at individual accounts in most cases. For example, Rubens painted lots of overweight women, so we know they were around, but statistics of an artist’s models says more about the artist than about the general population. Similarly, a 19 year old that weighs 500 pounds is a very rare event, even today. The primary reason we don’t call them fat freaks and put them in circuses is because making fun of abnormal people in person has become less acceptable, and if you do it on television you can find people that weigh more like a thousand pounds.
My point was more than Galen knew about people so fat Jerry Springer would want to put them on his show today, and the heaviest guy you see at a sci-fi convention is comparable to the heaviest guy you would see in the Roman Senate.
I am not sure the outliers (or the tails of the distribution in general) are relevant here. We know that there are metabolic disorders leading to obesity. It’s a pretty good bet that the 500-600 lbs people are metabolically different from the rest of the population and that was as true in the Roman times as it is now.
The real question is not whether the 500 lbs people existed in the olden times, sure they did. The real question is why does it seem that 250-300 lbs people were rare in pre-industrial ages and are rather common now (yes, I don’t know of good data on the prevalence of obesity before XIX century either...).
I don’t think it’s mostly a calorie availability issue. I don’t have a strong opinion on the cause, but if pressed I’d probably point to a confluence of factors including sedentary lifestyles, taste superstimulation and calorically dense foods (mostly refined carbs), stress, etc.
The real question is why does it seem that 250-300 lbs people were rare in pre-industrial ages and are rather common now (yes, I don’t know of good data on the prevalence of obesity before XIX century either...).
I agree that this is the real question; what surprised me was Eliezer’s confident empirical statement on a subject where all the weak data I have points in the opposite direction. It looks to me like the historical data suggests that calorie availability and sedentary lifestyles might be the primary explanations (and of the two, I would expect calorie availability to have a larger impact).
For comparison, this is what it takes to be the fat girl from the first decade of this century. She made the national news when she weighed 63 stone and had to be taken out through the wall of her house to go to hospital. 1 stone = 14 pounds.
Plenty of foods available today not available to our ancestors, such as semi-dwarf wheat.
Or Coke, for that matter.
But if the reason why we are fat and our ancestors were thin is that there are foods we have and they didn’t, and we don’t want to be fat, we can just not eat those foods. “[We are fatter than our ancestors because] food types have changed” only entails that you can’t affect your weight through your diet if you cannot choose to eat what your ancestors did.
Everything we eat has been bred for thousands of years. Does any of it have enough in common with our ancestors’ diets that “eat only that” can work?
I suppose one might look at what wild primates eat in the present day to answer that. Part of that is “smaller primates”, so that still might not be the way to go.
I meant “ancestors” on the timescale of one or two centuries (the time it took for the prevalence of obesity to rise from negligible to sizeable), not megayears. By “food types have changed” EY was referring to (I assume) availability of industrial superstimulus foodstuffs full of high-fructose corn syrup and whatnot.
Ok, I had thought this was going in the direction of the whole paleo thing. Eating as we ate a couple of centuries ago looks much more doable, at the individual level. (Changing the whole society would be a whole different thing.) But perhaps “eat food, mostly plants, not too much” is already one of the things EY has tried?
If you can eat “not too much” without your fat cells starving you to death, you’re probably already thin. I haven’t tried “mostly plants” because it’s vastly underspecified and I’m not particularly interested in being told afterward that I ate the wrong plants.
But perhaps “eat food, mostly plants, not too much” is already one of the things EY has tried?
Probably he has; but, unless the fraction of “metabolically disprivileged” people like him has been rising a lot in the past couple centuries, I guess that the rising prevalence of obesity means there are a sizeable number of people who haven’t tried that (seriously enough).
A simpler solution is just taking a piss. But do you really want to go into highly specific and precise definitions which take care of all technicalities? I don’t think you have anything to win there.
The laws of thermodynamics don’t require a fat cell to release lipids
No they don’t. But they require you to lose mass. Notably, CICO does not claim you’ll lose fat—it claims you’ll lose weight and in most cases some of that weight will come from fat and some from muscle.
Thermodynamics is not any more useful than quantum mechanics in understanding obesity.
I disagree.
I think it was Taubes who compared CICO to telling an alcoholic that it’s drinking alcohol that makes him an alcoholic. He used it as a put-down, but I’m totally fine with the metaphor. Understanding that is only the first step on a long and twisty road, but you have to make it. Otherwise people tend to believe that alcoholism can be fixed by, say, switching to drinking port from drinking whisky, or that as long as they take supplement X they can eat all they want.
I think for you (and many other people) CICO became associated with a moralizing stance of “you just need to exercise self-control to stop shoving things into your mouth and then your weight will be fine”—but it says no such thing (and the stance is stupid, of course).
Thermodynamics does rule out the case where people claim to stay fat and metabolically active enough to be alive despite eating very few calories, which apparently has been a thing.
Thermodynamics is not any more useful than quantum mechanics in understanding obesity. It is moralizing disguised as an invocation of natural law.
Mm… I guess what this would be a case of I agree with the connotations of what you’re saying, but not with the explicitly stated form, which I’d say goes a bit too far. It’s probably more fair to say “energy-in—energy-spent—energy-out-without-being-spent = net delta energy” is part of the story, simply not the whole story.
It doesn’t illustrate the ways in which, say, one might become unwell/faint without sufficient energy-in of certain forms, even if one already has a reserve of energy that is theoretically available to their metabolism, for example.
It’s probably a useful thing to keep in mind when trying to diet, for those that can usefully diet that way, but it’s not the whole story, and other info (much of it perhaps not yet discovered) is also needed. (And certainly using it as an excuse to moralize/shame is completely invalid.)
But I wouldn’t call it useless, merely insufficient. What is useless is to pretend that there aren’t really important variables that can influence the extent to which one can usefully directly apply the thermodynamics. (People who ignore the ways that other variables can influence the ability to usefully apply the thermodynamic facts and thus condescendingly say “feh, just eat less and exercise more, this is sufficient advice for all people in all circumstances” are, of course, being poopyheads.)
The only way to lose weight is to spend more energy than you consume.
Depending on what you mean by “consume”, that statement is false.
What about a converse statement?
Over the long term, an obese person can consume less energy than she expends while maintaining her weight and body form.
I’m confident this statement would be untrue in practice. Sure, the person could undergo reverse-liposuction, or retain more and more and more water, or have a fusion reactor in her spleen, but the laws of thermodynamics restrict possible scenarios to implausible ones.
The laws of thermodynamics don’t require a fat cell to release lipids because you’re hungry or exercising; the fat cells can just physically not react until your muscles run out of glucose or your brain overrules your attempt to starve yourself to death.
They don’t, but the reason we evolved fat cells in the first place was that they released lipids allowing our ancestors to survive during periods of scarcity who otherwise wouldn’t have. Of course there may be people for whom this mechanism is broken, but I doubt that John Walker, who claims to have lost a sizeable fraction of his body weight without surgery and not gained it back for decades, is lying.
Well, it is complicated.
Think of weight regulation as a three-layered cake :-)
The bottom layer is physics and CICO holds. The only way to lose weight is to spend more energy than you consume.
The middle layer is biochemistry. CICO still holds, but the energy output is a function of a large number of inputs (from genetic makeup to what kind of food do you eat). All the metabolic issues, insulin, leptin, ketosis, etc. live here.
The top layer is the mind. CICO still holds and all the biochemical mechanisms from the middle layer still hold, but now we add all the mental stuff—preferences, compulsions, eating-for-comfort, anorexia, eating as a displacement mechanism, etc.
And the cherry on top is that people are different. They have different metabolisms which work in different ways, they react differently to the same stimuli. No solution works for everyone and it looks likely that no solution even works for most. The only way out is to personally experiment and find out what works for you, for your personal, unique, and strange body and mind.
And we haven’t even touched the question of whether weight is the right metric to use (consider the alternatives, e.g. body fat % or general health even understood in a limited sense as absence of disease and normal metabolic markers).
So yeah, complicated it is.
Liposuction.
The laws of thermodynamics don’t require a fat cell to release lipids because you’re hungry or exercising; the fat cells can just physically not react until your muscles run out of glucose or your brain overrules your attempt to starve yourself to death. Similarly, there’s no rule that fat cells can’t die or shrink and the waste be dumped out through urine.
Thermodynamics is not any more useful than quantum mechanics in understanding obesity. It is moralizing disguised as an invocation of natural law.
Obesity rates used to be low. They’re now higher. The most obvious changes are higher food availability (and different food availability, read refined sugar/high fructose corn syrup/superstimuli fast food deliciousness), and more sedentary lifestyles. There may be other subtler changes, like the permanent psychological effects of being exposed to food advertising from a young age, and a million things that we don’t know yet, but there’s something out there, in the physical world, that has changed. And it’s not liposuction–that, and gastic bypass surgery, etc, didn’t exist a hundred years ago–their invention apparently hasn’t reduced obesity rates.
In summary, people moralizing about how obesity is just “calories in calories out” aren’t doing anything to solve the problem. But saying that thermodynamics is “moralizing disguised as an invocation of natural law” is just pointing out how not to solve the problem–it’s not helpful either unless you suggest an alternate solution. Or a list of 20 different things to try, at least 1 of which should work for >99.9% of the population. Or a drug that can target some mysterious fat cell receptor to make them cooperatively release energy during exercise/dieting. Or a special diet that empirically does the same thing, even if no one knows how or why. Or a way to raise children so that they have the same obesity risk as children 200 years ago. Or a way to at least treat the negative cardiovascular health benefits of obesity and make it harmless. Or liposuction. Etc etc etc. I don’t think people will get so mad about “moralizing” when this problem has a better solution.
...Oh, and a society that doesn’t massively penalize people for being chubby as long as their cardiovascular health is good would be a massive step in the right direction. As a normal weight girl who used to train in the pool every day, but still spent most of high school thinking I was fat and unattractive because of media images of models, I have a particular pet peeve with this.
In previous centuries, people rich enough not to have to worry about calories were rarely fat, certainly not at anything like modern rates. Food types have changed. Calorie supply seems like as much a red herring as the number of pirates or global warming.
Here’s someone fat enough to be a circus freak one century earlier:
http://www.coolcrack.com/2011/06/fat-circus-freak-century-ago.html
“Thermodynamics” doesn’t explain that change. Some significant number of people a century ago could afford to eat as many calories as they wanted. Also, are we supposing that the circus freak was exceptionally rich?
This statement surprises me. I had always heard that obesity was a sign of social status, but I never thought to wonder about the actual statistics for obesity among the rich. I’m finding statements like “common among the rich,” which suggests to me that rates are probably comparable to the modern American rate, but I’m not finding numbers.
It appears that medieval monks were obese at three times the rate of the general population [src], but I’m having trouble finding the actual paper or the actual rates.
And here’s a famously fat nobleman. I read recently about Dionysius of Heraclea, who grew so fat that he could not eat, and eventually so fat that he could not breathe. (There are several other examples there of people who grew too fat to move across the centuries, including a Roman senator who was only able to walk when two slaves carried his belly for him.)
A snippet of the linked article stands out. One Michael Edelman, weighing 1200 lb at his heaviest, in the end made serious attempts to lose weight. My emphasis:
Now, it’s clear from that article that all of these people ate massive amounts, but then, one has to ask why they did that. Just what are the causal connections here? What are the causal arrows going into the “overeating” node? To say “gluttony” is just giving a name to one’s ignorance and mistaking it for knowledge. What actually distinguishes someone to whom a triple chocolate muffin with chocolate sauce and a chocolate-coated chocolate flake on top with extra chocolate is a temptation to be resisted, from someone to whom it is not a temptation?
What other arrows are going into the “obese” node? What arrows are coming out of it and where do they point?
I don’t think anyone knows the answers to these questions.
The first place I would look is hunger and satiety hormones. It wouldn’t surprise me if their ability to tell themselves they’re full is broken, and so they’re hungry all the time, so they eat all the time.
That’s also what The Hacker’s Diet says.
I’ve heard this of Africa, but not of Europe. The reason that in preindustrial times millers were stereotypically fat is because it was assumed they pilfered a portion of the corn that farmers brought to them for milling. Friars (think of “Friar Tuck”) were stereotypically fat because they lived well (or were thought to) by visibly freeloading on the community. Neither class was well thought of for this. Being fat was taken as a sign not of status, but of idleness, sloth, greed, and gluttony.
As indeed it continues to be taken to this day.
So, nobles, merchants, monks, and millers were all more likely to be fat than farmers, and all were seen by farmers as idle, greedy, gluttonous sloths. It’s not clear to me why you think that means farmers saw them as having low social status, rather than resenting their high social status.
I think that by “status” he meant what Yvain calls “social power”, whereas you mean what Yvain calls “structural power”.
A famously fat nobleman? LIke, that was the fat guy from the seventeenth century?
I’m not sure. My point was more than Galen knew about people so fat Jerry Springer would want to put them on his show today, and the heaviest guy you see at a sci-fi convention is comparable to the heaviest guy you would see in the Roman Senate.
I’d be way happier with “this is the percentage of monks that were obese in 1400s Britain” to compare with “this is the percentage of Americans that were obese in 2000s America.” From the qualitative descriptions I’m seeing, the rich were obese at broadly similar levels to Americans today, and I’m having trouble finding quantitative descriptions. Are you aware of data I’m not aware of?
The trouble is that routine weighing of individuals wasn’t common until industrial times, records are spotty anyway, and so we’re forced to look at individual accounts in most cases. For example, Rubens painted lots of overweight women, so we know they were around, but statistics of an artist’s models says more about the artist than about the general population. Similarly, a 19 year old that weighs 500 pounds is a very rare event, even today. The primary reason we don’t call them fat freaks and put them in circuses is because making fun of abnormal people in person has become less acceptable, and if you do it on television you can find people that weigh more like a thousand pounds.
I am not sure the outliers (or the tails of the distribution in general) are relevant here. We know that there are metabolic disorders leading to obesity. It’s a pretty good bet that the 500-600 lbs people are metabolically different from the rest of the population and that was as true in the Roman times as it is now.
The real question is not whether the 500 lbs people existed in the olden times, sure they did. The real question is why does it seem that 250-300 lbs people were rare in pre-industrial ages and are rather common now (yes, I don’t know of good data on the prevalence of obesity before XIX century either...).
I don’t think it’s mostly a calorie availability issue. I don’t have a strong opinion on the cause, but if pressed I’d probably point to a confluence of factors including sedentary lifestyles, taste superstimulation and calorically dense foods (mostly refined carbs), stress, etc.
I agree that this is the real question; what surprised me was Eliezer’s confident empirical statement on a subject where all the weak data I have points in the opposite direction. It looks to me like the historical data suggests that calorie availability and sedentary lifestyles might be the primary explanations (and of the two, I would expect calorie availability to have a larger impact).
For comparison, this is what it takes to be the fat girl from the first decade of this century. She made the national news when she weighed 63 stone and had to be taken out through the wall of her house to go to hospital. 1 stone = 14 pounds.
And are the kinds of food our ancestors ate no longer available today?
Plenty of foods available today not available to our ancestors, such as semi-dwarf wheat.
Or Coke, for that matter.
But if the reason why we are fat and our ancestors were thin is that there are foods we have and they didn’t, and we don’t want to be fat, we can just not eat those foods. “[We are fatter than our ancestors because] food types have changed” only entails that you can’t affect your weight through your diet if you cannot choose to eat what your ancestors did.
Everything we eat has been bred for thousands of years. Does any of it have enough in common with our ancestors’ diets that “eat only that” can work?
I suppose one might look at what wild primates eat in the present day to answer that. Part of that is “smaller primates”, so that still might not be the way to go.
I meant “ancestors” on the timescale of one or two centuries (the time it took for the prevalence of obesity to rise from negligible to sizeable), not megayears. By “food types have changed” EY was referring to (I assume) availability of industrial superstimulus foodstuffs full of high-fructose corn syrup and whatnot.
Ok, I had thought this was going in the direction of the whole paleo thing. Eating as we ate a couple of centuries ago looks much more doable, at the individual level. (Changing the whole society would be a whole different thing.) But perhaps “eat food, mostly plants, not too much” is already one of the things EY has tried?
If you can eat “not too much” without your fat cells starving you to death, you’re probably already thin. I haven’t tried “mostly plants” because it’s vastly underspecified and I’m not particularly interested in being told afterward that I ate the wrong plants.
Probably he has; but, unless the fraction of “metabolically disprivileged” people like him has been rising a lot in the past couple centuries, I guess that the rising prevalence of obesity means there are a sizeable number of people who haven’t tried that (seriously enough).
No.
English can be surprisingly ambiguous at times.
A simpler solution is just taking a piss. But do you really want to go into highly specific and precise definitions which take care of all technicalities? I don’t think you have anything to win there.
No they don’t. But they require you to lose mass. Notably, CICO does not claim you’ll lose fat—it claims you’ll lose weight and in most cases some of that weight will come from fat and some from muscle.
I disagree.
I think it was Taubes who compared CICO to telling an alcoholic that it’s drinking alcohol that makes him an alcoholic. He used it as a put-down, but I’m totally fine with the metaphor. Understanding that is only the first step on a long and twisty road, but you have to make it. Otherwise people tend to believe that alcoholism can be fixed by, say, switching to drinking port from drinking whisky, or that as long as they take supplement X they can eat all they want.
I think for you (and many other people) CICO became associated with a moralizing stance of “you just need to exercise self-control to stop shoving things into your mouth and then your weight will be fine”—but it says no such thing (and the stance is stupid, of course).
Thermodynamics does rule out the case where people claim to stay fat and metabolically active enough to be alive despite eating very few calories, which apparently has been a thing.
Mm… I guess what this would be a case of I agree with the connotations of what you’re saying, but not with the explicitly stated form, which I’d say goes a bit too far. It’s probably more fair to say “energy-in—energy-spent—energy-out-without-being-spent = net delta energy” is part of the story, simply not the whole story.
It doesn’t illustrate the ways in which, say, one might become unwell/faint without sufficient energy-in of certain forms, even if one already has a reserve of energy that is theoretically available to their metabolism, for example.
It’s probably a useful thing to keep in mind when trying to diet, for those that can usefully diet that way, but it’s not the whole story, and other info (much of it perhaps not yet discovered) is also needed. (And certainly using it as an excuse to moralize/shame is completely invalid.)
But I wouldn’t call it useless, merely insufficient. What is useless is to pretend that there aren’t really important variables that can influence the extent to which one can usefully directly apply the thermodynamics. (People who ignore the ways that other variables can influence the ability to usefully apply the thermodynamic facts and thus condescendingly say “feh, just eat less and exercise more, this is sufficient advice for all people in all circumstances” are, of course, being poopyheads.)
Depending on what you mean by “consume”, that statement is false.
What about a converse statement?
I’m confident this statement would be untrue in practice. Sure, the person could undergo reverse-liposuction, or retain more and more and more water, or have a fusion reactor in her spleen, but the laws of thermodynamics restrict possible scenarios to implausible ones.
They don’t, but the reason we evolved fat cells in the first place was that they released lipids allowing our ancestors to survive during periods of scarcity who otherwise wouldn’t have. Of course there may be people for whom this mechanism is broken, but I doubt that John Walker, who claims to have lost a sizeable fraction of his body weight without surgery and not gained it back for decades, is lying.