Betting on weight loss... and losing: personal gambles as commitment mechanisms

摘要

Professional bookmakers rarely accept bets from individuals who directly control the outcome of the bet. We analyse a unique exception to this rule and a potential policy innovation in the battle against obesity: a weight loss betting market. If obese individuals have time-inconsistent preferences then commitment mechanisms, such as personal gambles, should help them restrain their short-term impulses and lose weight. Correspondence with the bettors confirms that this is their primary motivation. However, it appears that the bettors in our sample are not particularly skilled at choosing effective commitment mechanisms. Despite payoffs of as high as $7350, approximately 80% of people who spend money to bet on their own behaviour end up losing their bets. Empirical analysis of the betting market yields further insights. Males are treated very differently compared to females: being male is considered equivalent to having an extra 6 months to lose the same amount of weight. Movements in the market price also confirm the belief that rigidity is preferred to flexibility in setting successful weight loss targets.