Wording question help

Hello.  I contacted my insurance company and was told "diagnotic testing for obesity surgery is covered but the actual surgery itself is not."  WTF is that about?  I went higher up in the insurance totum pole and she said the same thing,  She also said thats the most asked question but the surgery is not covered.  Should I get all my clearances and see if I get denied?  I have been dieting and doing well but would like the surgery for lofe time benefits. Thank you.  )I have Atnea signature)