Our mass directly correlates with the energy balance because we can't make energy from nothing, we get it from stores of high energy compounds containing reduced carbon (Preferably fat, but strict diets can lead to loss of muscle mass as well). I've already explained the key assumptions that make the black box model perform so well, and I don't see a massive problem with any of them. Definitely not any that make weight loss impossible or an insurmountable task (i.e. requiring to eat minuscule amounts)

Entropy is irrelevant and I can't explain why if I don't know why you think it is (possible retorts: we don't use heat engines to perform work, the bulk of our food energy goes to heat and producing heat is always 100% efficient, the reaction rates are not dependent on Gibbs energy because of enzymes etc..).

I never said my black box model is completely accurate. It would be if we had all the parameters, but we don't. The calories-in part is 99% accurate and it helps that it's an upper limit. The calories-out part is harder to predict, but one can get close enough when considering just the basal metabolic rate necessary for survival, that even mechanically ventilated people need to live.

> We absolutely have anaerobic energy processes at work in our bodies every day. Muscle tissues are an example. The long tail variety of microorganism in our microbiome certainly includes plenty of other examples, our old friend yeast being a prime example.

First of all, I explicitly mentioned exercise as one of caveats. But unless you're a top athlete, it's a pretty small part of the energy balance anyways, and on my usual day my muscles are rarely starved of oxygen. And it still doesn't matter because it doesn't change the energy equation! The rest product of anaerobic fermentation in our body is a relatively high energy compound called lactate. We don't expel most of it, so it's not part of calories-out. It gets converted back into glucose and stays part of our mass. Same with the anaerobic microbiome. They don't make our feces more nutritious and they don't perform useful work (in the physics sense), so either they make heat or they expel high energy compounds that we then absorb and metabolize as part of calories-in.

I think it's unfair for you to accuse me of having blinders on. I don't pretend to know everything about the biochemistry of the human body. But I do know the constraints physics puts on it. I'm lucky that our body just so happens to work in a way that I can quite confidently state these things because of a few key assumptions that allow me to abstract over it using basic physics. I'm more than willing to revise my ideas, but you or someone else will first have to give strong facts which is not what I've seen here. One would also have to explain why caloric restriction works perfectly fine in a controlled environment (as many, many articles prove). Or simply explain how with a reduced caloric intake, one could supposedly stay alive without losing mass. Heck, as much as I rue anecdotal evidence, you can try it yourself.

> Here's the real problem: there is no direct correlation between mass and "willpower". Bringing up willpower here is slippery slope attempt to make a connection between weight and morality that is unjust at best. That is where the "calories in, calories out" rhetoric absolutely swerves to become more religious revival (the Protestant work ethic applied to food and exercise) than anything resembling science. Teach the controversy.

Good thing I'm Catholic then, and not even American. Diet is nothing but willpower. I won't pretend it's easy. Life is already hard and dieting takes a long time of fighting a basic instinct. But even if you don't believe in "calories-in, calories-out" (which I still don't think is justified), everyone believes in conservation of mass. If you eat less, you'll lose weight: http://blog.ifac-control.org/2016/12/05/closed-loop-weight-c...

I don't make any moral judgments about this, as I rarely do: I could never pretend to know another person's struggle. I don't think the recent obesity epidemic is a sudden widespread moral failure, but rather an change in environment that had an unexpected effect. But I also don't like ungrounded excuses, nor how quite a few of the comments on this page don't provide any evidence for quite extraordinary claims.