I get the idea large adult males can get up to 1500-2000 grams. But I've also heard you have to watch for obesity in older big males, because they can have heart disease problems. Sort of like older, big male humans?
But I don't worry about that with young males like Nergal. How old is he now?
My biggest male is George, the 2008 black pastel, at 1200 grams. George has been averaging a mouse a week for the last two years. You wouldn't think he'd be so big, but he eats EVERY WEEK, and he doesn't really fast during breeding season.
So we don't have a lot of 4-mouse weeks around here! Even the breeding females only do that a couple times in late summer.
EDIT: Did I say 1200 grams? I mean 1400 grams. Gosh, George! Sometimes I wish you were a female.