sounds like he doesn't need help, tell him how you feel.
I've been married for 13 yrs and I always liked curvy women but never knew of this fetish. When I first met my wife she was 120 and was in excellent shape....over the years she has gained and lost weight and is currently 190-200lbs....mostly because I know her weakness of certain foods and I make sure she gets them!
She knows I like her this size but she is still uncomfortable with it. She wants to lose weight and get back to a size 10 if not lower. I think she only wants too becasue her parents make comments to her (told me at Christmas) and worries about what other people say, otherwise she would stay this size. She gets to indulge and have a husband that loves her for it! So yes there are people in marriages that fatter their wives/husbands.