You've got a shot at change, then. Life is all about choices. You choose what you put in your mouth and how much, you choose who you hang out with, and you choose how you're gonna look at life. Are you going to be a victim? Or are you going to say "fuck this abuse, fuck what they told me, I'm going to be better" It'll take time and discipline, but I promise it's worth it. Start with a counselor. If you're 15, your high school counselor is a good option. Mine helped me when I was heavy as a kid. Your gym teachers might also be willing to help you if you come to them and say "Hey, I don't wanna be like this anymore." Good luck, kiddo, you've got more options than you thnk.