Don't forget that being past 300, 400, or higher takes a lot of extra eating just to maintain. A pigbeast that weighs 450 lbs could go on a "diet" of only 3500 calories a day and start losing weight. The biggest beasts (think 600 lb life) eat north of 8-10k calories per day. It can only be from a food addiction, even with a stretched out stomach most people start feeling sick after 4-5k calories in a 24 hour period.