Sure, you would love to completely just change your boyfriends eating habits but obviously everyone has a mind of their own and will end up doing what they want. So knowing this you have to change their way of thinking and this can be done without nagging at him like a mother would! You must set a good example! Eat healthy foods and brag about how good it feels to be healthy and that you wish that everyone could be as health concious as you are ;) Also make suggestions for eating healthy foods that taste good...Just because it's healthy doesn't mean it has to taste bad! Chocolate covered strawberries for example...delectable plus it's a fruit! Make him his meals! Although it's impossible to do this all the time but whenever you eat together make something you know he likes just modify it to make it healthier and point out the differences and how you made it healthier. And when you're out dining insist that he let you order and see how he likes it! If he's open to try new things then this should work out just fine...If he's not then all you can do is keep trying to get him to be more open minded.