birth control
"I was on Yaz for almost a year. I gained 25 pounds and am heavier than I've ever been in my life! I've never, ever had a problem with weight gain before. After being on it for a couple months, I started getting weekly headaches. Really bad ones. I decided to go off of Yaz to see if the headaches would go away and I'd stop gaining weight. Sure enough, after about 2 weeks the headaches stopped completely. I haven't gained any more weight either, and I've been off of Yaz for about a year now. Unfortunately, I'm having problems losing all the weight I gained!"