Really interesting hearing people say "who can stop at 10 cashew nuts?", "I could easily polish off a sharing bag of maltesers", or find it remarkable that someone can not eat an entire slab of chocolate and stop after one square.
I am one of these people for whom 10 cashew nuts IS enough. I'll eat them and think "that was nice, glad I did that" and stop at that. I won't proceed to "I'll just have another handful". I don't feel the need to. I have had a box of fancy chocolates in the cupboard since early December: one piece once a week is enough for me. I go days without even remembering it's there. I don't need to eat it, and I know it will be there when I do fancy a piece.
I don't physically crave any ingredient (sugar, fat, whatever) enough to eat an entire something. In fact, I think it would make me feel nauseous to eat too much of anything in one go - I guess it would anyone, but the question is what is "too much". An entire pint of Ben & Jerry's would definitely make me vomit. I will eat 1/3 cup at a time and that will be enough sweetness and fat for me. It won't fill me up, I'll have some tortilla chips after (sweet, savoury, sweet, savoury) but 1/3 cup is "enough".
And yes there is a moral element too: the sheer gluttony of a sharing bag of something, a whole slab of chocolate is repulsive to me on a moral level. That's down to my parenting, I think. I was raised in an "everything in moderation, except fruit and vegetables which you can eat to your heart's content" household. I think if I'd been raised in a permissive household, this factor wouldn't exist now.
Which still leaves the physical craving. I think some people have it, and some people don't. Just the luck of the draw. It must be a genetic thing as well as an environmental thing. Makes sense. Most of life is like that.