Bf overweight

Okay i'm not saying this as self centered but i am truly concerned for him. Less than a year ago my bf weighed 40 lbs less and was very fit. I know things change and stress and i'm not perfect but honestly i don't know what to do with him. Ive tried the friendly approach and he just isnt commited. I just want him to be happy because everytime we do anything sexual he complains about his weight and its such a turn off. I want him to be happy but he just doesnt. He just keeps getting bigger and idk what to do with him. (Please keep in mind that idc about how he looks its just that he has dramatically changed and is unhappy)