It is possible for your leopard gecko to get too fat but it’s not so common especially with a varied diet. So the most important thing is not to get overly concerned.
That said, if your gecko stands up and their belly is still dragging on to the ground, or they look obviously very rounded and are having difficulty moving, they might well be obese.
That’s easy to fix. As with humans, it’s about exercise and diet. For exercise you wanna ensure they move around a bit. For example, you could put their food in different places in the terrarium so they have to run around a bit to find them. Or you could play with them in a way that they get to move about. (see other posts about handling and playing with your gecko). As for diet, waxworms are excellent but they contain a lot of fat so make sure they don’t take up the largest proportion of a gecko’s diet.
Just remember that healthy adult leopard gecko’s have nice fat tails. Geckos store their energy in the form of fat in their tail. It’s healthy to have fat deposits behind their front legs too.
