I think keeping the weight on is security. Maybe we don't want the attention and we find men won't look when were fat. Heck, I find guys like a gal with some meat on the bones.
Sorry for the bad joke. But I have been told some men like a woman that isn't a toothpick. I am far from that nor do I want to be like that. I just want to feel comfortable in my skin. I figure I have to work on loving myself and then my loving of other people will be that much greater.