I have this problem too. My mum is more and more often now telling me what not to eat. "Don't eat too many of them pizzas, they'll make you fat". I just find it annoying, really, but I try to ignore it. I usually give off the impression that I'm happy the way I am. I wish I could just say "I like being fat and enjoy being a fatty!"
But if you're away in College, you have more freedom, you can eat what you like, whenever you like. I really envy that! But yes, as others have said, as long as you are happy that's the main thing