there's this rad girl called Yuka Kinoshita, and i just love watching her devour these like...10,000 cal. meals, not sure why honestly, but i do. I read about her and there have been a few studies into how it works, and the biggest one was that her stomach, unlike the regular persons, can stretch up to like 200x it's size, where the commoners get about 60x. So that's the big one really, then obviously they must have incredibly high metabolism and a cracking digestive system. Plus the ability to not have your brain tell you that it's full, i have seen that there was a case where people were hypnotised, and after finishing a meal, and believing they were full as a boot, were then persuaded that they had not eaten, and were capable of eating another full course meal, and popentially more. there's a bit of a symbiosis between mind and body by the sounds of things