Meta-analysis of the nine randomised controlled trials with data on body mass index found a significantly lower body mass index in the low fat arms compared with usual fat arms (−0.51, 95% confidence interval −0.76 to −0.26, I2=77%). Only one randomised controlled trial reported waist circumference. In the Women’s Health Initiative50 waist circumference in those on low fat diets was significantly lower than those on usual fat diets at five and seven years (by 0.30 cm, 95% confidence interval −0.58 to −0.02, 15 671 women)