Context Identifying effective strategies for treating obesity is both a clinical challenge and a public health priority due to the health consequences of obesity. Objective To determine whether common decision errors identified by behavioral economists such as prospect theory, loss aversion, and regret could be used to design an effective weight loss intervention. Design 3-arm randomized controlled trial in which participants were randomized to either usual care (weigh ins once a month) or one of two financial incentives arms. One incentive arm used deposit contracts in which participants put their own money at risk (matched 1:1 by the study) which they would lose if they failed to lose weight. The second used lottery-based incentives in which participants who met the weight loss target had each day a 1 in 5 chance of winning a small reward ($10) and a 1 in 100 chance of winning a large reward ($100). All participants were given a weight loss goal of 1 pound per week for 16 weeks, and results were analyzed using intention-to-treat analysis of variance models. Setting Philadelphia Veterans Affairs Medical Center. Patients 57 patients with BMIs between 30-40 aged between 30 and 70, with no contraindications for study participation. Main Outcome Measures Weight loss after 16 weeks. Results Participants in both incentive groups lost significantly more weight than participants in the control group (3.9 pounds); (Lottery = 13.1 lbs; p-value for lottery vs. control .014; deposit contract = 14.0 lbs, p-value vs. control .003). 47.4% of deposit contract participants and 52.6% of lottery arm participants met the 16-pound weight loss goal compared to 10.5% in the control group (p-value 0.014.). By the end of 7 months, substantial amounts of weight were regained; however, incentive participants weighed significantly less than they did at the study start whereas controls did not. Low lost to follow-up rates (7.0%) during the weight loss phase of the study suggest that both incentive systems were successful in keeping participants engaged in the study. Conclusions Incentive approaches based on behavioral economic concepts could have a major impact in reducing the incidence of obesity-related illnesses.

burned. Underlying differences in device accuracy may be compounded in these measures.Our study is limited by being conducted with young, healthy volunteers in a controlled setting with a convenience sample of a small number of applications and devices. Results should be confirmed in other settings and with other devices.Increased physical activity facilitated by these devices could lead to clinical benefits not realized by low adoption of pedometers. Our findings may help reinforce individuals' trust in using smartphone applications and wearable devices to track health behaviors, which could have important implications for strategies to improve population health. Role of the Funder/Sponsor: The National Institute on Aging, the US Department of Veteran Affairs, and the Robert Wood Johnson Foundation had no role in the design and conduct of the study; collection, management, analysis, and interpretation of the data; preparation, review, or approval of the manuscript; and decision to submit the manuscript for publication. Meredith COMMENT & RESPONSE Treating Chronic Knee Pain With AcupunctureTo the Editor In the randomized clinical trial of acupuncture for chronic knee pain, 1 the acupuncture treatment design appeared flawed. Specifically, the acupuncture points were nonstandardized and the study lacked the details necessary to ascertain whether the provided interventions were representative of acupuncture sessions appropriate for chronic knee pain. First, the acupuncture regimen was not consistent in the study, with some patients receiving less than 1 treatment per week, some patients receiving 1 treatment per week, and others receiving 2 treatments per week for 12 weeks. Dr Hinman and colleagues failed to report how many patients received 1 or 2 treatments per week. The commonly used frequency of acupuncture treatments for chronic knee pain due to osteoarthritis is 2 treatments per week for 8 weeks, followed by 2 weeks of 1 treatment per week, then 4 weeks of 1 treatment every other week, and finally 12 weeks of 1 treatment per month.2 Furthermore, no details were provided regarding depth of insertion or whether subjective deqi sensation was experienced by the patient. Deqi has been shown to be important to differential neurophysiological analgesic mechanisms in responders vs nonresponders to acupuncture.3 Hinman and colleagues also did not provide acupuncture with electrical stimulation, which not only has a dose-dependent effect on the degree of analgesia but also induces differential neurotransmitter responses depending on the electrical frequency used. 2,4The only conclusion that can be drawn from this study is that unsystematic acupuncture regimens did not result in significant clinical benefit to patients with chronic knee pain.

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BACKGROUND: Previous efforts to use incentives for weight loss have resulted in substantial weight regain after 16 weeks. OBJECTIVE: To evaluate a longer term weight loss intervention using financial incentives. DESIGN: A 32-week, three-arm randomized controlled trial of financial incentives for weight loss consisting of a 24-week weight loss phase during which all participants were given a weight loss goal of 1 pound per week, followed by an 8-week maintenance phase. PARTICIPANTS: Veterans who were patients at the Philadelphia Veterans Affairs Medical Center with BMIs of 30-40. INTERVENTION: Participants were randomly assigned to participate in either a weight-monitoring program involving a consultation with a dietician and monthly weigh-ins (control condition), or the same program with one of two financial incentive plans. Both incentive arms used deposit contracts (DC) in which participants put their own money at risk (matched 1:1), which they lost if they failed to lose weight. In one incentive arm participants were told that the period after 24 weeks was for weight-loss maintenance; in the other, no such distinction was made. MAIN MEASURE: Weight loss after 32 weeks. KEY RESULTS: Results were analyzed using intention-to-treat. There was no difference in weight loss between the incentive arms (P=0.80). Incentive participants lost more weight than control participants [mean DC = 8.70 pounds, mean control = 1.17, P= 0.04, 95% CI of the difference in means (0.56, 14.50)]. Follow-up data 36 weeks after the 32-week intervention had ended indicated weight regain; the net weight loss between the incentive and control groups was no longer significant (mean DC = 1.2 pounds, 95% CI, -2.58-5.00; mean control = 0.27, 95% CI, -3.77-4.30, P=0.76). CONCLUSIONS: Financial incentives produced significant weight loss over an 8-month intervention; however, participants regained weight post-intervention.