Polycystic Ovary Syndrome (thanks Wikipedia!). It's a fertility problem - my sister has it, but fortunately has still been able to get pregnant and recently had a baby daughter. It does apparently also cause weight problems in some women. I have no idea if there is a specific diet that can help, apart from the universal mantra of eat less, eat better food, and exercise more. My sister has never had a weight problem, so it's no good me asking her...