Yea I remember being a bit overweight when I started High school, bit joined football (Wasnt very good) and lost all of it and more. The triple practice days in the summer kicked my ass, and all the running, it dropped off in no time. I was 6'3 at around 240 and within a few months was 185 and felt great. Started off as a lineman, and then went to become an ok running back. really the key is just getting exercise at your age. Everything else will fall into place.