Testing Strategies for Weight Loss, II

Summary

In the pilot study, Testing Strategies for Weight Loss, we tested two different approaches using financial incentives to encourage weight loss. In the first, we built on previous work showing the effectiveness of 'deposit contracts', in which subjects are given the opportunity to put their own money at risk if they do not lose weight. In this incentive condition, subjects received a direct payment conditional on daily weight loss, and an optional additional payment based on their own contributions to the deposit contract. We matched their contribution 1:1 to make the option of depositing their own money attractive to this predominantly low SES population. In the second approach we built on our own prior work using lotteries to promote drug adherence. In this incentive condition, participants are entered into a daily lottery, and receive any payoffs they earn from the lottery only if they stay on track with their weight-loss goal. Given their popularity in the general population, lotteries hold the promise of providing a cost-effective means of motivating weight loss and making efforts to lose weight more salient to obese patients. Results from this trial indicate significantly higher weight loss in the incentive arms of the trial than in the control group. The low lost to follow-up rates suggest that this approach to providing daily feedback to keep weight loss salient among participants is feasible. Incentive participants who completed the study called in their daily weights an average 95.8% of the time. 17/19 (89.4%) of subjects deposited money in their deposit contracts and 14/17 participants who made initial deposits either held constant or increased their contributions each month. Subjects in both incentive groups lost significantly more weight on average than subjects in the control group (4.0 lbs) (lottery 13.1 lbs, p = 0.015; deposit contract 14.0 lbs, p = 0.003). Of the subjects not lost to follow-up in the two incentive arms (32 out of 38), all of them lost weight.

Based on this promising preliminary evidence and supplemental funding from the Hewlett Foundation, we propose an 8-month study with 2 intervention arms to further examine the effect of incentives on long term weight loss success. This study will build on the work to date to examine which intervention is most successful in promoting sustained weight loss. The proposed 3-arm extension will enroll 66 participants from Philadelphia VA with BMIs between 30 and 40, starting with those potential participants who were placed on a waiting list for our previous study after an overwhelming response to the initial mailing.

Conditions

• Obesity

Interventions

BEHAVIORAL

financial incentives

financial incentives based on attaining weight loss goals

Sponsors & Collaborators

• William and Flora Hewlett Foundation

  collaborator OTHER

• University of Pennsylvania

  lead OTHER

Principal Investigators

• Kevin Volpp, MD PhD · Philadelphia Veterans Administration Medical Center

Study Design

Allocation

RANDOMIZED

Purpose

TREATMENT

Masking

NONE

Model

PARALLEL

Eligibility

Min Age

30 Years

Max Age

70 Years

Sex

ALL

Healthy Volunteers

Yes

Timeline & Regulatory

Start

2008-06-30

Primary Completion

2009-06-30

Completion

2010-01-31

Countries

• United States

Study Locations