Heterogeneous Causal Effects of Financial Incentives on Weight Loss – Results of a Large Prospective Randomized Trial

In a randomized controlled trial involving 700 obese persons assigned to three experimental groups, we test whether financial incentives have heterogeneous effects on weight reduction. While two treatment groups obtain EUR 150 and EUR 300, respectively, for achieving an individually-assigned target weight within four months, a control group receives no such premium. The objective is to identify subgroups of patients (male/female, natives/migrants, etc.) who respond more than others to financial incentives. Our conclusions are the following: (1) monetary rewards effectively induce obese individuals to reduce weight across all subgroups; (2) the magnitude of the reward is relevant only for certain subgroups; (3) for people who do not lose weight via conventional weight-loss intervention programs, financial incentives are an effective supplement to induce weight loss.