is this as a staple food? i mean is your gecko skinny or just down a few grams? wax worms as a treat every now and them are fine and have more fat in them than anything else listed but they should be used sparingly. however if you just want to feed your geckos a good staple diet to fatten him up roaches are the best but not available all the time and some geckos are picky about them. so other than those the best to fatten up a gecko is just to feed it, i would start with mealies and as it eats i would go to supers. if this happens to be a gravid female a pinky every now and then is good to keep her weight up during egg laying season