Nine Randomised controlled trials (RCTs) were included (n=51,438). Sample sizes ranged from 40 to 48,835. Follow-up ranged from four months to 7.5 years.
One RCT (n=48,835) reported a small but statistically significant greater reduction in BMI (p<0.001) and weight (p=0.01) for a dietary intervention compared to a usual diet control group at 7.5 years follow-up. For comparisons of combined dietary and physical activity against control groups, greater reductions for intervention groups were reported in BMI for two RCTs (n=575, p=0.046 and p<0.001), and weight loss for three RCTs (n=642, p=0.046, p=0.01 and p<0.001). No statistically significant differences were reported between groups for BMI reduction in six RCTs (n=2,023) and weight loss in five RCTs (n=575)