I'm not sure I deserved the heat here. I prescribed no particular diet and said nothing about weak willed scum.

As you may have guessed, this isn't the first time the subject has come up. Frustration builds.

I'm of the tentative opinion that modern weight-control problems are just a case of human brains not being built for an environment of plenty.

It is not just the brain but the entire human body that isn't specialized for an environment of plenty. Lowered food intake changes metabolism and energy expenditure, it doesn't just make you crave more food.

Even if it was simply that people on average can't keep their hands out of the pastry box, that's not a moral failing, just an outdated adaptation. It's worth fixing ourselves because it's now a maladaptation and evolution is too slow about fixing it.

That would indeed still be true.

It seems to me that there must be some lower bound on food intake beyond which one can't help but lose weight -- otherwise you could eat nothing and still not lose weight, which seems spectacularly unlikely to me barring the aforementioned metabolic mutation.

That seems technically inevitable. The question then becomes whether this happens before or after your body enters a coma. (Or, more practically, whether valuable muscle mass is lost before undesired fat and whether the effect on fatigue and energy levels is debilitating.)