I strongly agree with part of this, and am reservedly skeptical about the rest. What I agree with is disputing "calories make us fat because thermodynamics". Yes, of course the laws of physics still apply, and energy in minus energy out has to equal stored energy... but there are all kinds of ways energy is entering and leaving the system.
I do think that calories eaten and expended are an important part of the equation - having seen some people lose weight through simply restricting portion size - but I am unconvinced that it is (or is not) typically the most important piece. I am convinced that "... because thermodynamics" is a poor argument for it being the only thing that matters.
(Calories eaten, calories burned, calories stored in fat cells) is not a closed system, so thermodynamics doesn't have a lot to simplistically say about it. There's also chemical energy stored in other forms, there's calories excreted, there's thermal energy in and out. Yes, there is clearly an extreme at which thermodynamics will force fat to be burned, but thermodynamics alone does not tell us whether that is meaningful when the goal is promoting long-term health (of which losing weight is, for most people, a meaningful piece).
I get that calories leave body in various forms but they get inside just in one. And if you eat less calories than you loose then you are bound to loose weight. No matter what crap you eat. It might not be pleasent. It might not be healthy but I think that it's almost surely more healthy than gut surgery and by transitivity than staying obese.
"I get that calories leave body in various forms but they get inside just in one."
That's not strictly true, though it might be a good enough approximation. Calorie is a measure of energy. If you're heated, energy is entering the thermodynamic system. Of course, thermodynamics tells us that converting heat into chemical energy is harder than the other way 'round, so it's unlikely our body is doing a lot of that efficiently.
"And if you eat less calories than you loose then you are bound to loose weight. No matter what crap you eat. It might not be pleasent. It might not be healthy but I think that it's almost surely more healthy than gut surgery and by transitivity than staying obese."
You're bound to lose weight, but the following is perfectly consistent thermodynamically: "all your muscle wastes away before your fat, then you die, then you can't keep up burning more than you eat". I'm not saying this is the case! I'm saying we need things other than thermodynamics to get any reasonable conclusion here.
Are you absolutely sure that there is a chemical process to convert extrnal heat into mass that is not neglible in comparison to how much mass is saved by the body when it does not have to heat itself at that temperature?
Because for me it looks like mentioning air pressure when we are trying to solve the problem of how some colliding masses of lead will behave. Strictly speaking air pressure could influence outcome but you won't see that in result with the accurancy you can humanly achieve.
As for your second point, we have a lot of experience with people starving themselves, even to death. And we pretty much know that fat is one of the thing that goes first. You can also look at people after gut surgery. Nothing special changes for them. They just can no longer eat vastly more than they need. And they loose weight.
I'm sure there are better more pleasant ways to loose weight and they will be eventually discovered, but there are sure relatively safe ways now.
"Are you absolutely sure that there is a chemical process to convert extrnal heat into mass that is not neglible in comparison to how much mass is saved by the body when it does not have to heat itself at that temperature?"
I'm not absolutely sure of much of anything, and that's my point. And I said it "might be a good enough approximation" to ignore it.
"As for your second point, we have a lot of experience with people starving themselves, even to death. And we pretty much know that fat is one of the thing that goes first. You can also look at people after gut surgery. Nothing special changes for them. They just can no longer eat vastly more than they need. And they loose weight."
And for the fifth fucking time I agree that there is evidence that eating fewer calories helps one lose weight - but to draw conclusions you need that evidence, not "simple thermodynamics", which is my entire point.
Nope, I understand your point, you're just still wrong for a pile of reasons that either I've been unable to express sufficiently clearly, you've been ignoring, or some combination thereof.
No one is suggesting that there's no thermodynamics involved. The objection is to using "thermodynamics, duh" as an argument. I generally encounter this in the stronger form of "the only thing that matters for weight loss is consuming fewer calories than you burn, because thermodynamics." That's obviously puerile. However, I think even in your more constrained (and better supported) usage here ("if you burn more energy than you eat, you will lose weight") it is still the case that you need to know other things about human biology; further, you need to know many more things to determine whether losing weight that way is advisable (even before incorporating the many physiological or psychological things that might mediate difficulty), which is the bit that actually matters.
These "many more things", we do have quite a bit of evidence regarding. But that evidence needs to be incorporated into the arguments to make the arguments meaningful.
Ok. I think I get your point now. I just don't agree.
> it is still the case that you need to know other things about human biology; further, you need to know many more things to determine whether losing weight that way is advisable
I believe that there are times when you need to be pragmatic and act before you know more. You might not be sure that losing weight (or that most obvious way to loose weight) is best for any given person but it's still an adivce they should take if they are overweight.
Just like it's a still good advice to excercise even if you are not perfectly sure that excersising won't kill you. You can take position of "I'm not sure. I better stay on my couch till the data comes in, indicating that it's healthy for me to run a bit." but that's not wise. You can't put yourself into stasis before you are sure if it's a good thing to eat less than you burn. Your life goes on and you need to act on incomplete knowledge you have so far.
TL;DR
I just don't agree that acting on "Do what physics tell you, ought to lower your weight." is worse than acting on "We need to learn more about our biology before we can do anything successful about our weight."
We knew plenty more than "thermodynamics" about losing weight before we knew about thermodynamics. I'm not saying "we need more study before anyone should make any changes to eating habits" - of course we need to operate off the best understanding we have (we certainly can't refrain from eating until we know everything :-P). My point is that reducing things to "thermodynamics, duh" is not doing that.
I do think that calories eaten and expended are an important part of the equation - having seen some people lose weight through simply restricting portion size - but I am unconvinced that it is (or is not) typically the most important piece. I am convinced that "... because thermodynamics" is a poor argument for it being the only thing that matters.