Hi, i'm 13 years old and i do not know what to do. My friends say i'm not fat, but i feel like i am. I am 7 stone 13 pounds and i do gymnastics 18 hours a week. I am not sure whether to go on a diet or not. Also, i am trying to get a six pack, but i don't know how to do so. I do sit ups and leg crunches but should i go on a diet too??