Analysis of an Online Tool for Creating Commitment Contracts for Weight Loss

INTRODUCTION: Commitment contracts are a behavioral economic tool where individuals make contracts with themselves to achieve a goal at a specified time. Individuals can put down money (“stakes”) to incentivize themselves to complete the goal; if they do not complete the goal, they lose the money.

METHODS: We obtained commitment contracts (n=5,278) for weight loss from a company that allows individuals to create online contracts. Individuals specified their own weight loss goal, time period, and self-reported their weekly weight. Our primary outcome was percent weight loss. We analyzed whether percent weight loss differed between those that did not put any stakes down and those that put stakes down in three different ways (charity, anti-charity, or to a friend). Using regression, we evaluated which factors were associated with the most weight loss.

RESULTS: When controlling for age, gender, previous contracts, contract duration, and number of friends/supporters, those who made anti-charity, charity, and friend contracts had more reported weight loss than those who did not put down stakes. Weight change was -4.95%, -4.19%, and -4.26%, respectively, compared to no stakes. Those with a wireless scale that automatically uploaded their weight automatically lost 0.94% less compared to those not using a wireless scale. Those with a referee lost 0.36% more than those without.

CONCLUSIONS: Commitment contracts may be effective tools to assist individuals lose weight. Adding a monetary incentive may increase the amount of weight loss, with the amount dependent on the type of incentive and whether another individual verifies their weight.