Anti-obesity effects of probiotics beyond BMI: a critical review of human clinical trials

The increasing prevalence of obesity worldwide has highlighted the need for adjunct strategies targeting metabolic dysfunction beyond simple weight reduction. This review aimed to evaluate the hypothesis that the anti-obesity effects of probiotics are mediated through modifications in fat distribution, metabolic inflammation, and appetite regulation rather than reductions in body weight or body mass index (BMI). A critical appraisal of recent randomized, double-blind, placebo-controlled human clinical trials was conducted, focusing on the effects of probiotic supplementation on adiposity, fat distribution, metabolic parameters, and eating behaviors. The evidence indicates that probiotic strains, particularly Lactobacillus gasseri and Bifidobacterium breve, are consistently associated with reductions in visceral fat, total body fat, waist circumference (WC), and body fat percentage, while effects on body weight and BMI remain modest. Strains of Lacticaseibacillus rhamnosus showed improvements in satiety. Probiotic supplementation with B. breve, B. pseudocatenulatum, L. plantarum Inducia were also linked to improvements in lipid metabolism, glucose homeostasis, inflammatory markers, and appetite regulation. Notably, several studies reported more pronounced effects in female participants. Overall, these findings suggest that probiotics exert anti-obesity effects primarily through metabolic and compositional changes rather than direct weight loss, supporting their role as a complementary strategy in obesity management.