well im a little bit tubby so all i can say is sometimes its not what you eat its your metabolism. My friend and I can eat the exact same amount of food (esp during summer when he is over here all the time) but he may loser some weight and im more likely to gain it.

anyways in north america, i saw a commercial describing it.

America, land of the all you can eat buffet
with millions of starving people every day.