A Cochrane review included 6 studies comparing a low glycaemic index or load diet (LGI) with other diet, with a total of 202 subjects. Interventions ranged from five weeks to six months duration with up to six months follow-up after the intervention ceased. The decrease in body mass (WMD –1.1 kg, 95% confidence interval [CI] –2.0 to –0.2, P < 0.05; n = 163), total fat mass (WMD –1.1 kg, 95% CI –1.9 to –0.4, P < 0.05; n =147) and body mass index (WMD –1.3, 95% CI –2.0 to –0.5, P < 0.05; n = 48) was significantly greater in participants receiving LGI compared to other diets. The decrease in total cholesterol was significantly greater with LGI compared to other diets (WMD –0.22 mmol/L, 95% CI –0.43 to –0.02, P < 0.05), as was the change in LDL-cholesterol (WMD –0.24 mmol/l, 95% CI –0.44 to –0.05, P < 0.05). No study reported adverse effects, mortality or quality of life data.
Comment: The quality of evidence is downgraded by study quality (unclear allocation concealment) and by imprecise results (few patients and wide confidence intervals).