LRHillian

Denise, this is just one of the requirements that MANY carriers have. It's not a "no," it's a "we don't have enough information yet."
DON'T GIVE UP!!! Worst-case scenario, you start a six-month relationship with your PCP tomorrow. If you've been seeing doctors over the last few years for ANY reason, get their notes. It's possible/likely that their notes include comments on your weight.
I had Aetna too, and what I supplied was notes from my OB/GYN from the two deliveries of my children, which had happened within the prior five years. So there were lots of notes on my weight, even if they didn't involve attempts at weight loss. And in 18 months prior to banding, I'd been seeing my PCP regularly to talk about weight loss, surgery, my thyroid, etc., and all of those notes counted as well.
This is a minor hurdle. Historical records from any doctor will do to support the five-year-history requirement. And if you can't supply the six-month diet attempt, get started NOW. Six months will go by before you know it.