Aetna PPO
I have Aetna. You have to meet ALL of their criteria, and they will usually deny you on the first try anyway. If you go to their website, it should tell you specifically what the criteria are, BMI, co morbs, etc. I do remember that they require 6 months minimum Dr documented diet history, within the past two years, and it has to be a physician supervised diet - Weigh****chers, etc, is not good enough.
However, once they approve, they do pay quickly, so your physicians aren't left wondering when the bills will get paid.