Feeding any animal what amounts to junk food full-time just to add weight is probably a bad idea. Waxworms are high fat, and great as a treat or a regular RARE occurrence (my gravid girls are getting 1 or 2 twice a week, along with their regular food variety). Too much fatty food with otherwise poor nutrition (which is what waxworms are) will be bad for your gecko in the long run. A better option might be dubia, discoid, or lateralis roaches, which have a good protein content.
Just thought I would post a follow-up since I haven't been on in so long. Stripe's been eating a meal of 8-10 mealworms and 1-2 waxworms coated in calcium every three days and is gaining weight. I'll lower the number of waxworms soon. I think she shed last night, but some bits of unshed skin on her feet still haven't come off. They've been there for a month or so now and I don't know if I can remove them without hurting her. I've tried bathing, using a wet q-tip, tweezers, blunt fingernail scissors, and my fingers in an attempt to get them off, but (mostly) to no avail. Any suggestions? I don't know if I could really afford a vet trip at the moment.