Study participants will be obese volunteers recruited from a major community-based weight loss program (Weight Watchers), who have lost at least 5kg during the 4-6 months prior to enrolling in the study. Among these participants, the following will be assessed: 1. The effectiveness of a daily lottery-based financial incentive, relative to the control group, on weight loss and weight maintenance; 2. The effectiveness of a direct payment incentive, relative to the control group, on maintenance of weight loss; 3. Assess the comparative effectiveness of lottery-based and direct payment financial incentives on weight loss and maintenance; 4. The degree to which weight loss is maintained in the intervention groups relative to usual care during the 6 months following cessation of the intervention will also be determined.
During Phase I, incentives will be provided to some study participants (direct payment and lottery arm) for the first 6 months and subjects will be followed for 6 more months to examine effects following cessation of incentives.
