OBJECTIVE: To identify and review published interventions aimed at the prevention of weight gain. DESIGN: A systematic review of published interventions aimed at the prevention of weight gain. METHODS: Search strategies-we searched eight databases, manually checked reference lists and contacted authors. Inclusion and exclusion criteria-studies of any design, in which participants were selected regardless of weight or age, were included. Interventions targeting a specific subgroup, multifactorial interventions, interventions aimed at weight loss, and those with an ambiguous aim were excluded. Data extraction-data were extracted on behaviours targeted for change, psychological model, behaviour change methods and modes of delivery, methodological quality, characteristics of participants, and outcomes related to body weight and self-reported diet and physical activity. Classification and validation-a taxonomy of behaviour change programmes was developed and used for classification of underlying model, behaviour change methods, and modes of delivery. The data extraction and subsequent classification were independently validated. RESULTS: Eleven publications were included, describing five distinct interventions in schools and four in the wider community. Where diet and physical activity were described, positive effects were usually obtained, but all were measured by self-report. Effects on weight were mixed but follow-up was generally short, Smaller effects on weight gain were found among low-income participants, students and smokers. Many participants in the community-based studies were overweight or obese. Study dropout was higher among thinner and lower-income subjects. CONCLUSION: Interventions to prevent weight gain exhibited various degrees of effectiveness. Definite statements about the elements of the interventions that were associated with increased effect size cannot be made as only one of the five studies that involved an RCT design reported a significant effect on weight. This intervention involved a correspondence programme and a mix of behaviour change methods including goal setting, self-monitoring and contingencies. Future interventions might be more effective if they were explicitly based on methods of behaviour change that have been shown to work in other contexts. Effective interventions would be more easily replicated if they were explicitly described. Effectiveness might be more precisely demonstrated if more objective measures of physical activity and diet were used, and if the follow-up was over a longer period.
