A lot of these questions are contingent on the program thru the hospital. As long as the surgery is medically necessary and you go thru their pre op program and released for surgery by their people you should be good. I know Blue Cross in general requires a 6 month supervised diet (I have blue cross). This means monthly visits to the surgeon, nurse practitioner, dietitian at the facility. Once thru their program, they will put in for the authorization for surgery. As long as you follow the guidlines you should be good.