Thats difficult but I try to educate men about how bad that stuff is and also how much cheaper it is for you to shop and cook and how much fun it can be. Maybe watch top chef and have a friend come and cook with you. At first maybe make desserts and transition to healthier foods. Kind of like saying if you want your sweets you have to eat the healthy stuff. Maybe he doesnt like your cooking? I like stuff like stirfry my bf doesnt care for it. Every now and then i make it for myself. Also soup. Let him have his fast food on those nights. But make things he really likes to start following a recipe and he'll get used to it. Its like starting a dog on new dogfood lol. We crave what we eat all the time. He can crave carrots as much as burgers.