Background: A low-glycemic index (GI) diet may be beneficial for weight management due to its effect on insulin metabolism and satiety.
Methods: Obese children aged 9-16 y were randomly assigned either a low-GI diet or a low-fat diet (control group) for 6 mo. Body composition changes were measured by dual-energy X-ray absorptiometry and bioelectrical impedance analysis. Insulin sensitivity was measured by fasting plasma glucose and insulin.
Results: Fifty-two participants completed the study (mean age: 12.0 ± 2.0 y, 35 boys); both groups showed significantly decreased BMI z-score but similar changes in fat and fat-free mass. The low-GI group demonstrated a significant decline in fasting plasma insulin (22.2 ± 14.3 to 13.7 ± 10.9 mU/l; P = 0.004) and homeostatic model of assessment-insulin resistance (4.8 ± 3.3 to 2.9 ± 2.3; P = 0.007), whereas the control group did not. However, general linear model showed no significant difference in insulin resistance between groups after adjusting for baseline levels, suggesting that the greater reduction in insulin resistance in the low-GI group may be explained by higher baseline values.
Conclusion: Despite subtle effects on body composition, a low-GI diet may improve insulin sensitivity in obese children with high baseline insulin. A bigger study in obese children with insulin resistance could be worthwhile to confirm our findings.