I'm so sorry you've had to deal with this. It's not right. My body seems to have been and still is a topic of comment a lot. As a thin woman, I have no recourse, I can't say anything. As a woman, I do. But people seem to forget that men have feelings and insecurities too. Men are actually human, I know, I married one, LOL.
Nobody should be commenting on anyone's body, end of story.
If nobody's told you today, I'm proud of you for taking charge of your health. It's not easy. That's something a man does, not a 12 year old boy.