Gastric Byp Surgery?

I am wanting to have Gastric Byp surgery but my insurance told me they would only cover it if I am 200% overweight. Well I was wanting to try and figure out if I was before I went all the way out of state to meet the doctor and get no where. I am 5'9" 375 lbs and my BMI is 56. Could someone please either tell me a way to figure out my % of overweight or if you already know the answer. I really need to know ASAP! Thanks guys!!!