There is more at work here than just how much garbage one can tolerate. I see it in my two sons - one loves to eat, takes comfort from food, and has to mind his weight; the other certainly enjoys food, but if you offer him something to eat and he's not hungry, he says no, and he'll leave food on his plate if he's full, and just generally has a different relationship with food. What they like and choose to eat, however, is quite similar.
-S-