Money can motivate us to do just about anything and that apparently includes losing weight. A pair of behavioral economists ran an intriguing study in which subjects enrolled in a 16-week diet program with the goal of shedding 16 lb. Some of the volunteers became part of a lottery arrangement in which those who met or exceeded the goal would win a cash prize. Others were part of a deposit-contract arrangement in which they anted up their own cash, with the pot being split among those who did the best. The remaining volunteers had no cash incentive. The results? At the end of the 16 weeks, 53% of those in the lottery group reached the 16-lb. goal; in the deposit-contract group, it was 47%. The group with no prize on the line finished a distant last, with an 11% success rate. Once the cash dividends stopped, the weight loss did too, and most subjects gained back much of it. Still, the investigators believe that if the program ran for 12 to 18 months, participants would start to reap physical benefits that would provide a deeper incentive on their own.