My attention whore cat is driving me crazy! help! begs for food, wants to be on top of me every second!?

I moved in with a roommate that came along with a cat. There are three of us ,but I'm the only one home most of the time. The cat is fed in the morning and at night, but begs for food constantly! If you even take a step in the general direction of his food dish, he runs toward it and loudly meows. The meows get worse and worse. They start to sound like whining and crying after a while. Despite the begging, we never break the feeding pattern and give in yet it continues. The cat will also follow you from room to room, brush your leg if you stand still, jump in your lap if you sit down, get in your face and climb on you when you're sleeping, etc. If you close your door it will meow and scratch at the door. I've shut it downstairs and it manages to turn the handle and get out. If you prop something up against the door the cat will start throwing itself against the door. It's actually kind of scary! It sounds like the weight of an adult human being thrown against the door! Help me! It's starting to feel like I'm stuck in some sort of cat horror movie!