Introduction: Behavior patterns have been identified, which may help explain why people put a greater emphasis on immediate gratifications (eg, the pleasure of eating) than delayed benefits (eg, enjoying good health). These insights lead to the development of two incentive-based approaches to weight loss evaluated in this study.
Methods: A total of 57 healthy adults with a body mass index of 30 to 40 kg/m2 were included in the 16-week study. Study subjects were randomized to 1 of 3 regimens and followed for 4 months. The regimens included: a) a weight-monitoring program involving monthly weigh-ins (control group), b) a direct economic incentive, or c) a lottery incentive. The direct economic incentive group was invited to contribute money to a “matching fund” in which up to $3 per day of their money would be matched and augmented by study administrators, such that if the patient continued to lose weight throughout the month, they could “earn” as much as $252 per month. Money deposited by subjects (the amount deposited was selected by the participant, from 1 penny to $3 daily) into the “matching” account was not returned to the depositor if weight was not lost; instead, it was pooled and given to persons at the end of the clinical trial who had lost at least 20 pounds (in addition to whatever additional “winnings” they had accrued). In the lottery group, there were periodic lotteries during each month, and if the study subject had continued to lose weight on the day of that lottery, he or she could win funds up to $100 for each lottery. All subjects were provided with a 1-hour session with a dietitian focusing on diet and exercise.
Results: Mean weight loss at 16 weeks was significantly greater in the economic incentive and the lottery incentive groups (13.1 lbs and 14.0 lbs, respectively) compared with the control group (3.9 lbs; P=0.02 and P=0.006, respectively). The target weight loss of 16 lbs was reached by approximately half of the subjects in the incentive groups compared with 10.5% of the control group (P=0.01). At 7-month follow up, while the net weight loss between the incentive groups (9.2 and 6.2 lbs) and the control groups (4.4 lbs) was not statistically different, subjects in the incentive groups weighed significantly less than at baseline (P=0.01 and P=0.03, respectively). The average cost of the programs over the 16-week period was $378.49 in the deposit contract group and $272.80 in the lottery group.
Conclusion: Offering financial incentives to lose weight appears to be effective for short-term weight loss. The benefits of the programs were not fully sustained at 3 months after the programs ended. The authors called for studies assessing longer-term use of incentives to determine whether this would lead to sustained weight loss.
Commentary by Louis Kuritzky MD
Limitations of traditional non-surgical weight-loss methodologies are well recognized: only modest weight loss is attained, and regain of weight post-treatment is the rule rather than the exception. If we go back to fairly basic incentive-reward methods, might patients with the need to lose weight be more motivated and hence more successful in losing weight were they to be directly rewarded by a cash incentive? That question was addressed by this randomized trial in otherwise healthy obese adults.1
Both the economic incentive and the lottery incentive group lost statistically significantly more weight than the control group (13.1 lbs, 14.0 lbs, and 3.9 lbs, respectively). There is, however, a potentially discouraging bit of a “post-script”: in a 3-month post-trial follow up (off incentives), substantial weight regain occurred, such that over the full 7-month interval (4 months active treatment plus 3 months off treatment) there was no statistically significant difference between the groups for overall weight change. We do not know whether continued incentive-based intervention would have continued to support weight loss.