Do they not make chew things for cats like pigs' ears, "leather" bones, or other hard things that take hours to eat? Perhaps your vet can help you out with that. If he is occupied for a few hours with something like that, it might be the way to break the habit. When you give him what he wants, he is training YOU. But get him medically checked out for worms, I agree.
My friend's "fatcat" takes over the bowl and bullies the other cats from eating. She has to feed the others away from him, just so they can get food also.
Is he alone, or does he have a playmate? Can you give him one of those toys that you fill with loose food, and he has to play with it to get the food out? (but at night he should be resting more).

These are questions for a behaviour expert!

Good luck,