I eat loads but i am not that fat, why?

Well you're not fat because you don't eat loads. I eat more than you do and i'm not fat either. People who say they only eat a breakfast bar or whatever are full of crap or enjoy starving themselves. You sound perfectly healthy to me. Don't worry about what other people eat either, thats their business. And if they start to comment on how much you eat, just beat em with the torpedo roll :)