I agree with Starmom - you don't want to overfeed a male....
I have a couple boys that are over 1000gms that can eat a med rat, but I still give them smalls. They don't need to get fat or they will be too lazy to get their job done.
Big girls get smalls and mediums - and they are getting fat!! And hanging out on the cool side, laying inverted and hanging out in their water dishes....
Fun times!!!