Seth Roberts, a UC Berkeley professor in psychology, has an unusual theory on weight gain: whenever you eat a food that is flavorful and familiar, your body demands that you bank as many of those calories as possible. What if you could keep your thermostat low by sending fewer flavor signals? He eventually found two ways of doing so: by swallowing a few tablespoons of either unflavored oil or sugar water in between meals, he was a lot less hungry. He and his friends and colleagues have lost weight and have not gained it back.