I feed my adult leo only molted superworms. I always have at least a thousand at any given time for my bearded dragon. At night, I dig through the rubbermaids and find a few that are molted (white & soft) and drop them in the tank.
He LOVES them and since I started feeding them will not touch crickets. I have only had him about a month, but he's gained around 12 grams in the short time I have has him. He's got a nice, plump tail and is quite active.
I hate crickets with a passion - they stink, they're gross, loud and carry diseases (coccidia is a PITA!)
As soon as I get around to it, I'm going to order some Phoenix worms - I bed he'd love some of those. I raised my beardie on those (and the occasional silkie) so if you can pick some of those up, they may be a good idea as well...just another option. 
-----
0.1 American Bulldog - Maui
0.1 Shiba Inu - Mako
1.0 Pit Bull - Magnum
2.0 White DSH Cats - Lucaya (Luke) & Fiji
1.1 Ferrets - Demolition & Derby
1.0 Sunrise Corn Snake - Tequila
1.0 Orange Bearded Dragon - Orin
0.0.1 Albino Leopard Gecko - Ed