How can I lose weight quickly?

Well, im 12 and i weigh 113 and im 5'1. I feel like my belly is chunky like i have more of a bigger stomach then my body needs i guess. All of my friends are in shape and skinny and they eat a whole lot more than i do. i am really active im outside playing or jogging swimming lots of sports. i don't exactly want to lose weight but some but also become stronger and i will never go on starving my self or baby carrot diets.Please help me.