How do I tell my husband to start watching what he eats?

So my husband is getting out of the army really soon and he is no longer required to do PT (physical training). Since then he hasn't cared to work out on his own and he has started doubling, almost tripling, the amount of food he eats every day. Most of it is lots of sugar, cookies, soda, etc. he is starting to gain lots of weight really fast and I'm really worried and concerned for his health. I told him that we both should try to be healthier and start working out together, I cook healthy meals and buy healthy groceries but he goes out and buys himself sugary sweets any ways. When I tell him that I want him to take care of his health he just rolls his eyes. How do I tell him he's gaining weight and needs to stop eating so much and working out without hurting his feelings? He is kinda sensitive about the subject....