This randomized controlled trial aimed to determine the effectiveness of financial incentives based on behavioral economics in promoting weight loss. The study involved 57 participants with BMIs between 30-40, aged 30-70, who were randomized to either usual care or one of two incentive arms: a deposit contract and a lottery-based incentive. Both incentive groups showed significantly greater weight loss (13.1 lbs and 14.0 lbs, respectively) compared to the control group (3.9 lbs) after 16 weeks. Additionally, a higher proportion of participants in the incentive groups met the 16-pound weight loss goal (52.6% and 47.4%, respectively) compared to the control group (10.5%). Despite substantial weight regain over 7 months, incentive participants weighed significantly less than at the study start, while controls did not. The low loss-to-follow-up rate (7.0%) suggests that both incentive systems effectively engaged participants. The study concludes that incentive approaches based on behavioral economic concepts can significantly impact obesity-related health outcomes.This randomized controlled trial aimed to determine the effectiveness of financial incentives based on behavioral economics in promoting weight loss. The study involved 57 participants with BMIs between 30-40, aged 30-70, who were randomized to either usual care or one of two incentive arms: a deposit contract and a lottery-based incentive. Both incentive groups showed significantly greater weight loss (13.1 lbs and 14.0 lbs, respectively) compared to the control group (3.9 lbs) after 16 weeks. Additionally, a higher proportion of participants in the incentive groups met the 16-pound weight loss goal (52.6% and 47.4%, respectively) compared to the control group (10.5%). Despite substantial weight regain over 7 months, incentive participants weighed significantly less than at the study start, while controls did not. The low loss-to-follow-up rate (7.0%) suggests that both incentive systems effectively engaged participants. The study concludes that incentive approaches based on behavioral economic concepts can significantly impact obesity-related health outcomes.