And like humans (and other animals) weights can vary widely from animal to animal depending on their body types.
I have a 50g female that looks pretty chubby... and on the flip side I have a lean looking 85g male.
It is hard to get leos to lose weight once they've gained it but as long as you follow the rule of moderation you should be okay. Feed a healthy staple like crickets or roaches and supplement with other insects. As long as you don't over do on the fatty stuff your gecko should maintain a healthy physique.
My female is considered over weight according to the vet, she is 75g'. However she never got fat like this until she hooked up with our male about 5 months ago since then she has just gotten bigger and bigger. When shes healthy she'll eat until i take her food away from her, so i would say you probably could over feed them.