Advice

So I recently Judy got back together with an ex from 4 years ago and he's always been a big guy, but he's just gotten even bigger. And I was laying on his chest and he was just breathing so loudly, like omg, it scared me. And I'm worried about his health. I'm 5'11 260 pounds. How can I bring it up in a conversation like "Oh babe both of us need to go on a diet or try to work on our health better" without him fstow about it. I dont want to hurt his feelings I really love him. And I dont want to make it just about him. I'd rather involve myself too.