I've heard of "keeping males lean" for breeding

[Adam_Wysocki]

Adam, how can you tell if a ball python is fat vs. naturally big?

I believe that it's more experience than anything else ... once you've had your hands on 4, 5, 6 hundred different adult ball pythons, you begin to get a "feel" for how an individual animals "body type" is and what that "good breeder" weight would be.

-adam