Plus you're fighting genetics - or at least I am. All the women on my Mom's side of the family are heifers (so are the men) and they don't really eat any differently than anyone else.
From my standpoint genetics do play a major factor. I don't know a single direct relative that was overweight. I used to be 5'9" and since I was 16 I've weighed about 145. I can eat anything I want and anytime I want and it just doesn't make a difference. I like to eat just before going to bed at night and all it does is make me sleep with a full stomach.