My roommate is upset because she thinks her boyfriend's diet and exercise habits are endangering his health. We're trying to figure out ways that she can help him, but the problem is he doesn't think he has a problem and gets very defensive about it. He's 21, 6' and nearly 300 lbs. He won't even walk anywhere, and refuses to go to the gym, even when she goes. She says that all he does is play video games all day. On top of that, he drinks 5 750ml bottles of Coke a day and won't even drink the diet stuff, and eats out all the time (even when my roommate cooks for him). She doesn't really care that he's fat, just that he's endangering his health. He refuses to let the doctor check his blood pressure or pulse, so nobody knows how unhealthy he really is. We can't really think of any good way of motivating him to improve his habits. Does anyone else have any good advice?