Yes, because they store fats and nutrients in their bodies. If they are thin at all, that means they are not being taken care of properly, and are not being fed. Or it could mean that they have parasites or a serious illness. A leopard gecko is too fat if its belly drags on the floor even when its running, and it has overly large armpit bubbles. Your gecko looks nice and healthy to me, just avoid waxworms and youll be good