Caloric expenditure is not strictly a function of behavior. Holding all else constant, including amount of exercise, reducing caloric intake will also reduce expenditure.
I know, this is why when people stop dieting and return to their original level of consumption, they sometimes end up heavier than before, as Janet mentioned. It’s usually better to increase exercise rather than decrease calorie intake, but this thread is about diet, so I haven’t really gone into that.
Sometimes it will reduce it by more than the reduction in intake.
Not to say it can’t, but I’ve never heard of this happening. Reference, please?
Once again, it seems I’ve stated my position badly. I really shouldn’t have used the word “simple” in my opening post. Nothing in biology is simple.
I’m not trying to say you can cut food willy-nilly and still be healthy. I’m not trying to use energy balance as a curiosity stopper. I’m trying to use it to combat claims that you can eat as much “good” food as you want as long as you avoid “bad” food.
I was using it to mean “arbitrarily much food”. My position is similar: If you eat just until you’re full and you get moderate exercise but you’re still overweight, you should talk to your doctor. You may still need to change your eating or exercising habits, but you should do research first, and not make any sweeping changes all at once.
Changing your habits is always difficult, and that’s where the willpower comes in. It should only be needed until you settle into your new habits, though. And you should never have to be constantly hungry, or end up having to eat almost nothing, as Janet said. Both outcomes are extremely unhealthy.
I think I’ll add this to my original post to clarify my position. I seem to have come across as more extreme than I intended.