First of Sarah never ever compare ur self to ur friends. Thats wrong to do. Ur never gonna look like ur friends. We are all different. i think 131lbs for age 13 is good. But it all depends on how u feel about urself. So i think really u should cut down on the amount u eat every day. Like when school starts, if ur allowed to, bring a water bottle to school every day. when u eat dinner cut every portion in half. Drink more water than juice and soda. If u want u can mix more water in to take away the sugar a little. Workout for an hour at least 3 days a week. keep urself occupied-u wont think about food. And remember eat only when u are hungry, and dont eat to get full only enough to satisfiy u. Thats about it, BYE AND GOOD LUCK.