Metabolism.
If you want a fast metabolism, snack all day long and don't eat full meals, you'll be able to do this sort of thing.
I deliberately slowed my metabolism down a bit, just by eating breakfast, light lunch and dinner without snacking (and drinking water) for a few weeks. I used to be able to eat about two full large size pizzas in a meal and feel alright, now I eat six of eight slices of one and I'm fine.
It's generally a better idea not to let your metabolism get too fast, otherwise you'll just end up unnaturally skinny/wiry no matter what you do. There's people around here who eat large meals five times a day and are like 60kg because of their metabolic rate.
Those people also drink like nobody's business when they get going; and piss like six times an hour when they're drinking. Whereas I can't really handle more than six to eight drinks an hour and barely piss at all.
6'0" exactly and about 76kg. Forget how that converts to pounds.