So I'll go out a bit more on a limb, and observe that A: I had some lightweight metabolic illness (ate bad as a child, ate better as an adult but definitely had lingering effects) and B: I really don't seem to anymore, noticeably so even after three weeks. I can eat a lot more carbs and even a bit of outright junk, and I'm still losing weight right now. (While successfully exercising for strength gain.) That was not true two months ago; I had to rigidly stick to my low-carb regime, and any deviation plumped me right back up. Again, I'm still not ready to call it after three weeks, but the thought is certainly stirring in my head that this could be a nontrivial element of the obesity problem, and a nontrivial reason why dieting often seems to hit a plateau early and often, before it really should. In theory, even in our current food environment, it ought to be possible to get pretty close to our natural, optimal weight without having to torture ourselves, precisely because it is the natural weight for us. In practice, it's quite hard.

(There's a blog post bubbling in my head about how Everything I Was Told About Health As A Child Was Entirely Wrong. Not just sort of wrong, but "everyone needs to eat three meals a day"-is-also-wrong levels of absolutely, positively everything I was told is wrong. The only thing I can think of that was true is that exercise is important, but even then, there was a radical overemphasis on aerobic exercise when I now believe the correct focus for most people is strength training.)