Effects of probiotics and synbiotics on body weight management in individuals with overweight or obesity: a systematic review and meta-analysis of randomized controlled trials.

PURPOSE: This meta-analysis examined whether short-term probiotic/synbiotic supplementation reduces body weight, BMI, fat mass, body fat percentage, and lean body mass in adults with overweight or obesity.

METHODS

Electronic databases were searched for RCTs of probiotic or synbiotic interventions versus placebo. Study quality was assessed using the Cochrane Risk-of-Bias tool. Standardized mean differences (Hedges' g; RevMan 5.4) were pooled using a random-effects model on post-intervention endpoint values.

RESULTS

Ten RCTs (633 participants) were included. No significant differences were observed in body weight (9 studies, n = 592; SMD = -0.44; 95% CI: -0.92 to 0.04; I2 = 87%) or lean body mass (5 studies, n = 342; SMD = -0.14; 95% CI: -0.53 to 0.25; I2 = 69%). A significant reduction in BMI was identified (10 studies, n = 633; SMD = -0.50; 95% CI: -0.91 to -0.09; I2 = 84%), and a small but significant effect on fat mass/body fat percentage was observed (8 studies, n = 479; SMD = -0.34; 95% CI: -0.62 to -0.06; I2 = 57%). In sensitivity analyses excluding a study with pre-randomization baseline imbalance, the BMI effect attenuated to borderline significance (SMD = -0.45; p = 0.048) and the fat mass/body fat percentage effect lost statistical significance (SMD = -0.26; p = 0.060).

CONCLUSION

Short-term (8-12 weeks) probiotic/synbiotic supplementation may yield modest benefits on BMI and adiposity-related outcomes; however, sensitivity analyses indicated these effects were not robust to single-study exclusion. Body weight and lean body mass were not significantly affected. Use of post-intervention endpoint values (change-from-baseline scores were not consistently available) may have biased pooled estimates. Findings should be interpreted as preliminary.