Obesity remains a significant problem in the United States, even among youth. Upwards of 14% of adolescents have severe obesity, defined as having a body mass index (BMI) of at least 35. 1 Because youth with obesity tend to become adults with obesity and are at significant risk for accompanying comorbidities like diabetes and cardiovascular disease, weight loss while still in adolescence is optimal.Of course, if weight loss were easy, then we wouldn't have an obesity epidemic in the first place. 2 Sustained weight loss is very hard to accomplish, even with significant effort. This month's JAMA Pediatrics features a successful effort, however. 3 It combined financial incentives with meal replacement therapy, or MRT. MRT, which involves providing participants with all their meals for extended periods, has not resulted in substantial results over time. Could paying for behavior change improve its impact?Paying people to change their behavior has shown promise in a number of domains. Years ago, I wrote on economic incentives for a variety of patient behaviors. 4 While the incentives I wrote about then failed to get people to take their medications, there were some promising results concerning smoking cessation and weight loss.This most recent study randomized adolescents aged 13 to 17 years with severe obesity into 1 of 2 arms. The first was MRT, in which they were provided all their meals preprepared to achieve a well-balanced consumption of about 1200 kcal/d. These meals were provided free of charge and delivered to their homes. The second was MRT plus financial incentives, where, in addition to all of the above, patients were paid $20 in the form of a gift card for every cumulative 0.5% reduction in their body weight from their baseline.The good news is that the intervention worked. Although 29% of participants were lost to follow-up, 89 completed the 1-year visit. Those who received the financial incentives in addition to MRT lowered their BMI by a mean of 2.6 in a year compared with only 0.3 for MRT alone. They lost a mean of 5.7% of their body weight compared with a 0.5% weight gain for MRT alone. The financial incentives cost a mean of $330.77 per person.The authors argue that giving financial incentives plus MRT are cost-effective above MRT alone, with an incremental costeffectiveness of about $39 000 per quality-adjusted life-year gained. However, this doesn't account for the cost of the meals, which is also significant.Therefore, this study showed that by providing adolescents with severe obesity with all their meals pre-prepared, delivered, and free, and also paying them an average of $330,