I read your post and did a little research. I'm new to PCOS and I hadn't heard of a GI Diet. but I found this website
http://www.annecollins.com/low-glycemic-index-diet.htm
It says, a GI Diet "reduces cravings and leads to better blood-sugar control". the website gives sample menus and explains what it is. I'm assuming cause with PCOS we have a harder time regulating our sugar that this diet is designed to help regulate it.
As I said I'm newly diagnosed to PCOS so some of the veterans might have better or more experience and knowledge regarding this. Good luck.