Everyone has a different build and body type. My mate Greg was extremly overweight when he was younger and is very fit now as an adult. Pay attention to what your eating. Start replacing your sweets with things that taste good, but are lower in fat and calories. Get invovled in a sport activity (or learn to skate board, or something other activity that gets you moving). You are still young and growing, so do not diet too much. Get support from your family and realize you are the same as your mates(just maturing on a different schedule). Love yourself and your body, and NEVER let anyone make you feel inadequate:)