My cat needs to loose weight, like ASAP!?

Try feeding Milo and Grace at separate times. Put one cat into another room when its feeding time, and place a restriction on Milos food. So what he gets, is all he gets. While Grace is well feed. Try using a weight loss brand of cat food. And ignore him when he throws a trandrum, he'll stop once he finds out no one is reacting to his fits.