I go through stages when I crave something chocolate. Usually Godiva, a Symphony bar, or those little Italian chocolate mint sticks... It doesn't happen monthly and doesn't seem to be related to hormones at all for me. It's more like every three months or so. I'm not sure why I want it when I do, but I've found that I actually consume LESS calories and make healthier choices if I give in (in small amounts) to my cravings when I have them. Which means a bag of hot fries every 4-6 months, and chocolate a little more frequently.
