Because many people just aren't able to get that ratio to a point that they're at a healthy weight (for numerous reasons - behavioral, medical, etc.).
"Assuming no changes in behavior" doesn't make sense, because the drug makes people feel full after a smaller amount of calories and thus changes behavior.
Don’t you ever eat sweets despite of not being hungry? I don’t think the issue is people overdosing rice or legumes because they are so hungry. The issue seems to me like quick comfort foods that we eat not to get full but because they just feel so good in our mouths. I don’t think I’ve ever eaten ice cream out of hunger:)
Yeah, I agree with all of that, but I would differentiate slightly between not being hungry and being full. I snack when I'm not necessarily hungry, but I don't snack right after I've eaten a full meal and am actively full.
Anyway, semantics of hunger/fullness aside, the effect of the drug is behavioral - people taking it do end up eating significantly less, which leads to substantial weight loss.
Also it is much easier to pass those snacks and other stuff when you are full or not hungry. If this is consistent state, it can also effect how accessible at other times snacks and such are.
"Assuming no changes in behavior" doesn't make sense, because the drug makes people feel full after a smaller amount of calories and thus changes behavior.