He's not going to lose weight until HE wants to. It's nearly an impossible task when someone wants to lose weight very badly. In his case, where he doesn't want to do it at all, it's hopeless.
All you can control is what you eat. If you're in charge of all food purchasing, then don't buy those high calorie foods. If they're not there, he can't eat them unless he gets in the car and goes and buys them.
You could tell him of your concerns for his health. He might be receptive to your help if presented in a kind and loving way. Good luck