More Money, Less Weight

December 17, 2008
Shivani Parmar, MPH

Researchers in PA found that using money as an incentive for people to lose weight might just be the answer.

In an effort to identify incentives for encouraging people to lose weight, Pennsylvania researchers have found that money might be the perfect answer. Taking an unusual and innovative approach, scientists tried 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.”

In the study results published in the most recent issue of the Journal of the American Medical Association, researchers from the Philadelphia Veterans Affairs Medical Center, the University of Pennsylvania, the Wharton School , and Carnegie Mellon University wrote that “behavioral economics has identified several patterns of behavior that help explain why people engage in self-destructive behavior, including the tendency to put disproportionate emphasis on immediate gratifications, such as the pleasure of eating, relative to the much smaller emphasis put on delayed benefits, such as enjoying good health.”

To test this, scientists recruited 57 healthy volunteers between ages 30 and 70 with body mass indexes ranging from 30 to 40. Three weight loss plans were created to which participants were randomly assigned. The control group participated in monthly weigh-ins. The other two groups consisted of incentive-based approaches. “One was a lottery-based group in which the participants played a lottery and received the earnings if they achieved or lost more than the target weight and the other was a deposit contract condition in which the participants invested their own money, which they lost if they failed to achieve weight goals.” All participants were randomly assigned and had a goal of losing 16 pounds over the course of 16 weeks.

By the end of the study, the incentive groups lost considerably more weight than the control group. The lottery group lost an average of 13.1 pounds, the deposit contract group an average of 14 pounds, and the control group an average of 3.9 pounds. About half the participants in both the incentive groups met the 16-pound weight-loss target, while only 10 percent of the control group met the target. Monetarily, the deposit contract group earned an average of $378.49 and the lottery group an average of $272,800.

It is important to note that the “study participants in both of the incentive groups gained weight between the end of the weight loss incentive intervention and the end of 7 months, but still weighed less at 7 months than they did at the start of the study.”

The authors concluded that “incentive approaches based on behavioral economic concepts appear to be highly effective in inducing initial weight loss. However, this weight loss was not fully sustained and further work is needed to test the effectiveness and cost-effectiveness of these approaches in achieving sustained weight loss.”