I would suggest you investigate the prospect that the fundamental human condition involves "dopamine addiction", as dopamine activity is literally the thing our brain does to trigger pleasure in our mind - it is the primary neurochemical mechanism of that feeling. Dopamine-moderated pleasure, or some variant of it, is a basic drive (perhaps synonymous with 'basic drive', with motivation itself) that we likely share with the entirety of the animal kingdom.
http://en.wikipedia.org/wiki/Reward_system
http://en.wikipedia.org/wiki/Dopamine#Animals
http://www.slate.com/articles/health_and_science/science/201...
I would also point out that fat people very rarely eat much above their natural metabolic burn rate. Instead, people who are presently gaining weight are doing so. Someone who eats an extra 500 calories per day over what their body demands (call it one, one and a half grilled cheese or PB&J sandwiches) gains 1 pound per week, and has gained 52 pounds after 1 year. A fat person who has a stable weight is not eating excess food. The reason you see them eating more food than you, is that when we gain weight, our body demands more energy to feed that body mass; Losing a pound at 130lbs weight requires a similar amount of discomfort & deprivation as losing a pound at 330lbs weight. For them to be feeding a body two and a half times as large on a similar diet as a stable-weight 130lbs person, would represent a very rapid, very uncomfortable weight loss, a starvation diet.
Usually, people gaining weight put on pounds slowly; Gaining 26 lbs per year is a 250 calories per day excess. They're only eating 10 or 15% more than they should be to maintain their weight. This is not the behavior of an out-of-control addict chasing the dragon, but a largely functional feedback loop responding to a slight artificial bias in favor of extra food, or less exercise, than it's naturally tuned for (or at least, than it was subjected to previous to the obesity epidemic).