Effects of isolated soluble fiber supplementation on body weight, glycemia, and insulinemia in adults with overweight and obesity: a systematic review and meta-analysis of randomized controlled trials.

Systematic review and meta-analysis of 12 randomized controlled trials including 609 adults with overweight or obesity. Participants were generally weight-stable and otherwise healthy at baseline, with several trials enrolling Asian cohorts; intervention periods ranged from 2 to 17 weeks.

Isolated soluble fiber supplementation was evaluated versus placebo/control across 12 randomized trials. Doses varied by study and arm, including 3 g/d to 6 g/d for 12 weeks, 10 g/d for 6 weeks, weight-based dosing around 0.14 g/kg, and higher-dose regimens up to about 30 g/d; administration was oral and typically daily.

Isolated soluble fiber supplementation improved several body composition and glycemic outcomes versus placebo, supporting a beneficial role for weight management and glucose-insulin homeostasis. Pooled effects favored soluble fiber for BMI (−0.84, 95% CI −1.35 to −0.32; P = 0.001), body weight (−2.52 kg, 95% CI −4.25 to −0.79 kg; P = 0.004), body fat (−0.41%, 95% CI −0.58% to −0.24%; P < 0.001), fasting glucose (−0.17 mmol/L, 95% CI −0.28 to −0.06 mmol/L; P = 0.002), and fasting insulin (−15.88 pmol/L, 95% CI −29.05 to −2.71 pmol/L; P = 0.02). Waist circumference and HOMA-IR were not significantly improved, and between-study heterogeneity was substantial for several outcomes.

Interpretation is limited by substantial between-study heterogeneity, short intervention durations (2 to 17 weeks), and variability in dose and population characteristics across trials. Some outcomes were not consistently reported, and adverse events were not synthesized as a separate outcome in the extracted data.