Diets that require expenditure of willpower fail because the willpower expenditure indicates that something is going wrong with your body

I seem to be able to come up with various willpower draining activities that are useful, so how should I proceed if I wanted to know a particular diet is such an activity instead? Evolutionarily speaking hunger is clearly an indicator that something is wrong, but I'm not sure how that translates to values of a modern obese human.

Strangely enough, these same weak-willed dieters often seem to have little trouble exercising hard - for years on end, maybe - though often to no avail, of course.

Well, exercise is known to have other benefits than weight loss, so I wouldn't encourage people to stop moving their bodies on those grounds. Also, this seems to be the kind of useful activity I was talking about.