Omega-3 Improves Your Pet Health

My roommate and I have cats – one is mine and one is hers. My cat has always just eaten whenever he feels like it, and only a few bites. He is slim and in good health. My roommate’s cat is very overweight, and whenever there is food available he shovels it in with huge gulps. After doing this, he almost always throws up, then goes right back to do it again. It’s disgusting! My problem is that I can’t leave food for MY cat out, else the other one eats it all, leaving my cat with no food. I am having to shut my roommate’s cat out of the room which forces my cat only to eat when I can do that. And when I shut the other cat out of the room, he knows my cat is eating and he retaliates by shredding the furniture or spraying.
How do I stop this other cat from eating so much in such a short amount of time and/or retaliating when he can’t get to the food?