I have Tricare Prime with Triwest and they cover the lap band with prior authorization. I went to my PCM and got the referral. Had the consult with the surgeon and within a few weeks was banded.
Be sure to also have your office visits and fills authorized for coverage, otherwise you are responsible for a co-payment.
You will need to have a co-morbidity to qualify quickly.
Also if you have diabetes, after you have lost the weight, your PCM can refer you to a plastic surgeon for a Tummy Tuck - so long as the excess skin sometimes gets "rashes" from heat and sweat.