We identified 68 studies: most consisted of short-term (≤ 12 mo) treatments using diet (n = 8), exercise (n = 4), diet and exercise (n = 10), lifestyle (n = 19), orlistat (n = 25) or metformin (n = 4). Compared with the control groups, intervention participants had a greater mean weight loss of –3.02 kg (95% confidence interval [CI] –3.52 to –2.52), a greater reduction in waist circumference of –2.78 cm (95% CI –3.34 to –2.22) and a greater reduction in body mass index of
–1.11 kg/m2 (95% CI –1.39 to –0.84).