The Effects of a Commitment Device on Health Outcomes: Reputational Commitment and Weight Loss in an Online Experiment

This article tests the effectiveness of commitment devices on weight loss. It can be applied as a health ‘nudge' that locks in future behaviours to achieve a desired health outcome, by staking money or reputation on achieving that goal. A field experiment randomly assigned 364 clients of an online weight loss service to either a reputational commitment device or an upfront refund on the monthly fee. The reputational commitment intervention was expected to combat time inconsistency and promote greater weight loss. Weight outcomes were measured at 12 weeks. The results showed that all experimental groups lost weight on average, but the group experiencing the reputational commitment reported end weight outcomes 1.5 kg higher than the comparison group, indicating slower weight loss (± 0.05, effect size -0.32). One possible explanation for the findings is ‘commitment overload'. The study nuances the understanding of commitment devices and how best to deploy them in health programmes including e-heath platforms.