What should I do?

Your friends need to knock it off!! You need to tell them straight up that you accept this guy for who he is and what’s in his heart not for looks. Have a talk with your friends and, him and, you need to tell him that he’s not fat or anything. You made the choice to date him and you also made the choice to accept him for what he is not for looks. If your friends claim to be your friends then they need to stop insulting your boyfriend and, respect him. This has caused him to think that he’s fat and your friends have put him down and that makes him to do that to himself. Talk to him, tell him that everythings going to be alright and, that you’ll talk to your friends and tell them to stop insulting you. I’ll put some encouragement for him, Sir, you are not fat and all that, you’re just perfect and, stop putting yourself down and, accept the way you are. Anyway, that’s my encouragement for him. So, you too talk about it and, make those friends of yours stop right away. Good luck and I hope that you too will make this relationship last.