Introduction: Childhood obesity often results in insulin resistance (IR) and may cause type 2 diabetes. Fibers are described as a dietary intervention controlling hyperglycemia; however, their effect on obese children is understudied.

Aim: To assess the effect of fiber supplementation on IR in obese children.

Methods: A randomized controlled trial was carried out at Cairo University Children’s Hospital (Cairo, Egypt), including 123 obese children aged 6-13 years. Two-step double blind randomization using sealed envelopes was done. Step 1: randomization into an intervention group (82 subjects) and control group (41 subjects). Step 2: randomization of the intervention group for either receiving 10 g/day of powdered psyllium or a high fiber diet. Fasting insulin, glucose, C-peptide and homeostatic model assessment of IR (HOMA-IR) were measured at baseline and after 8 weeks for all participants.

Results: Fasting glucose, insulin, C-peptide and HOMA-IR were significantly reduced with psyllium (p < 0.001 for all) and natural fibers (p = 0.001, < 0.001, < 0.001 and < 0.001 respectively), while they were increased in the control group (p = 0.09, 0.006, 0.015 and < 0.001 respectively). The median percent of change from baseline for HOMA-IR was -26.47% and -42.55% compared to +9.38% for the natural fiber group, psyllium group and controls respectively. Psyllium induced better HOMA-IR profiles as compared to the other 2 groups (p < 0.001). Both interventions similarly reduced BMI and waist for height z-scores compared to the control group. We report no serious side effects of psyllium; however, unpalatability was a frequent complaint (40.5%).

Conclusion: Both psyllium and natural fibers improved IR in obese children but this improvement was more pronounced in the psyllium group.