Financial incentives for extended weight loss: a randomized, controlled trial

Abstract

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.

Figures

Figure 1

Flow of study participants.

Figure 2

Mean cumulative weight loss at 8 months (primary outcome measure) and approximately 17 months.

Figure 3

Deposit contracts: a) proportion of participants who made a contribution, by whether the weight loss goal had been attained in the month prior; b) Mean and median amounts deposited, by month.