Husband gaining weight

My husband has never cared how he looks and often needs to be told things like its time for a haircut or that is shirt has a stain. However, he's gaining quite a bit of weight. A lot of his clothes dont fit and he's just noticeably bigger. Hes anxious to have sex again soon and I feel like part of the reason I'm less inclined to want it is because he's heavy. I dont know how to address this with him since he is still clearly attracted to me even with my postpartum body.