Yeah, even a fuzzy rat is going to be waayyy to small for that guy, so yeah he's still hungry.
Get yourself a rat or mouse that is at least as big around as he is, and offer one every five days. He'll eat like an elephant for a while, then he'll level off and only want to eat every 7 - 10 days.
No matter how big he eventually gets, don't go bigger than a small rat, about 60 grams, because he doesn't need anything bigger than that, no matter if he weighs 2000 grams.
Gale