Every insurance company has different criteria. Your Surgeon's office should know the ins and outs of what's required for your insurance company. They should also get with them early and determine exactly what is required. In my case, Aetna, I had to do 3 mos Dr. monitored weight loss (that was a joke), Psych eval (3 hour questionaire, what a pain in the ass), and cardio workup. It probably helped that I had high blood pressure and had been diagnosed with Sleep Apnea the year before.
It seemed like a lot of hoops to jump through, but it's been well worth it. I have a flexible spending account as part of my benefit package. I was able to spread my OOP ($2,500) over each check pre-tax...GREAT BENEFIT!
Good luck to you!