Oh Gina, I wish I could give you a big hug. My ex wasn't MO, but he was over weight. He was forever failing the body fat tests when he had to do his PRT. At 6'3" he flucuated between 250 and 230. When he got back from deployment, seeing I had lost 80 pounds and was now 10 pounds less then his lowest, he changed.
He never told me he was proud of how I looked. Only that I was sexy and how turned on he was (can o worms, stopping that line of thought

).
Anyways, when I started getting healthy and lost all the weight, he became jealous. He didn't start eating any better. In fact, it got worse. He always had chips around and ice cream...because he knew I couldn't have it. I would get off the scale in the morning and be thrilled that I lost a few pounds and he'd mumble "must be nice".
I like the idea of talking to him, but not about his weight. He needs to know that you feel there's something not quite right. That was my mistake, I never talked to him to tell him how I felt.