Type the search terms "obesity" and "FSFI" in Google Scholar and you should immediately get multiple hits. There is already a lot of research in this area.

Dear Carey,

I found your request today only. If you are still looking for it...

http://www.unizar.es/gine/FSFI6seclim.pdf

http://connect.asmbs.org/PDF%20Documents/Press%20Releases/2010/Sexual_Dysfunction_ASMBS%20Release.pdf

http://www.pglocomotor.com.br/images/online/producao_67738_Evaluation_of_sexual_.pdf

https://sciencescape.org/paper/20394615

http://www.edc.pitt.edu/pdf/papers/soi130132.pdf

If you still need it just let me know that I can give you some others. If these are not exactly what you need you can also just give me a little bit more of information to focous even more according to your needs.

Hope you these may be of any help.

Vilemar Magalhães