NEED HELP WITH LETTER OF SUPPORT FOR AETNA

 Ok so to make a long story short.. I am supposed to be having surgery next month and I have Aetna. I have gone above and beyond to complete all required testing, classes, and follow up's. I have to have everything submitted to Aetna this month for approval. There is one thing holding up this very stressful process.. MY PCP! He is not by any means like your average doctor. I have been going to him for 3 years and he has never once weighed me! When I asked him to write the letter of support he told me to write it myself and he will sign whatever I put down in this letter. If I include past weights and BMI's from  2011-2013 in this letter "from my PCP" would that be considered a presence of sever obesity that has persisted for at least 3 years as documented in "contemporaneous clinical records?" Please help me! I have come to far to let this ruin everything. I'm just at a loss.