Only 10 trials qualified for inclusion in this review. Existing trials varied by intensity, delivery methods, target groups and study components, and therefore provide limited opportunities for comparison of effect size. Five studies reported a significant difference in weight between intervention and control subjects of between 1.0 and 3.5 kg, due largely to an increase in weight in the control group. Further large, effective, evidence-based programmes are urgently needed in the general population as well as high-risk groups.

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