My girl can be quite aggressive at times and full of attitude despite her small size. I get quite a kick out of her simply because she has such a spunky personality. My one males is the same: large and lazy. I wouldn't worry about putting your frog on a diet unless he is actually obese. Males are wanted for their size-not their activity. That's why you need the girls!! ....and if you ever want to try breeding, too, I guess.