The Gym/junk food lifestyle

I have a friend who is always at the gym but has a very poor diet consisting mostly of junk food. I can?t make him understand that this is bad for him. Plus, he really overdoes things at the gym often staying on a single machine until there is a puddle of sweat on the floor. If his fitness is so important to him, why does he eat rubbish? How can I convince him to get a better lifestyle with better food and less gym?

My housemate is very similar. I often worry about her, but she knows it isn't healthy and does it anyway - there is nothing I can do

the only way to get him to eat less junk food is to show him that stuff thats healthy for you can still taste just as good!! at the gym challenge him at different machines, do a mile on one then move on.

He probably thinks it all balances out or something. Maybe you can try adn sort out some sort of exercise schedule for him or something?