Motivational processes and the persistence of weight‐loss dieting

Objectives. The principal aim was to determine whether ‘controlled’ motivation can account for differences in persistence with weight‐loss dieting. The study also investigated whether goal‐setting attributes moderated or mediated the relationship between controlled motivation to diet and persistence with dieting. Design. A 2 × 2 between‐subjects design was used, with controlled motivation (low versus high), and type of feedback (positive versus negative) as the independent variables. This design enabled the investigation of their separate and interactive effects. Method. In a vignette study, 100 females were told to imagine they wanted to lose 3 kilograms. They then answered questions concerning their individual weight‐loss goals. Controlled motivation was assessed via a questionnaire. Two predetermined schedules of reinforcement for the dieting created a positive and a negative feedback group. The number of weeks for which the participants indicated they would continue dieting provided the index of dieting persistence, or the outcome measure. Results. The findings revealed that those with highly controlled dieting motivation persisted with dieting for longer than those whose motivation was less controlled, irrespective of whether weight was lost. Goal specificity moderated the effect of controlled motivation on persistence, and commitment to weight‐loss goals partially mediated the contribution of controlled motivation to persistence. Conclusions. To understand variability in the persistence of weight‐loss dieting, we need to invoke differences in the nature of motivation to diet and specific weight‐loss goal attributes. Prevention strategies should aim to encourage autonomous decision making among young females, especially in relation to weight‐loss dieting.