Body Weight, Dieting and Obesity Traps

This paper presents a theoretical investigation into why losing weight is so difficult even in the absence of rational addiction, time-inconsistent preferences or bounded rationality. We add to the existing literature by focusing on the role that individual metabolism has on weight loss. The results from the theoretical model provides multiple steady states and a threshold revealing a situation of ''obesity traps" that the individual must surpass in order to successfully lose weight. Given such a threshold we investigate if a short-run incentive scheme for weight loss is able to promote persistent weight-losses and what features an incentive scheme should have in order to sustain permanent weight loss. We find that a lump-sum incentive scheme is not always able to lead the individual to permanent weight loss. On the contrary, a non-decreasing incentive scheme with rewards for weight loss according to levels of body weight (i.e. progressive), is able to sustain a steady state reduction in body weight and food consumption.