Influence of Lactobacillus plantarum on anthropometric and inflammatory parameters in obesity: a GRADE-assessed systematic review and meta-analysis of randomized controlled trials.

BACKGROUND: The global obesity epidemic, rooted in chronic inflammation and metabolic dysfunction, necessitates novel interventions; however, evidence regarding the efficacy of Lactobacillus plantarum remains inconsistent. OBJECTIVE: To evaluate the impact of L. plantarum on obesity-related outcomes in adults via a systematic review and meta-analysis of RCTs. METHODS: Following PRISMA guidelines and registered in PROSPERO (CRD420251102722), we systematically searched PubMed, Cochrane Library, and Google Scholar through May 2025. Eighteen RCTs (1310 participants) involving non-diabetic adults with BMI ≥ 25 kg/m² were included. Primary outcomes were body weight and BMI; secondary outcomes included lipid profile, glycemic indices, inflammatory biomarkers, liver enzymes, and body composition. ROB 2.0 and GRADE were used to assess bias and evidence certainty. RESULTS: L. plantarum supplementation significantly reduced body weight (MD = -1.23 kg; 95% CI: -1.97 to -0.49; p = 0.001; I² = 49%) and BMI (MD = -0.28; 95% CI: -0.54 to -0.02; p = 0.03; I² = 77%). Subgroup analysis suggested these reductions were more pronounced with multi-strain formulations than single-strain L. plantarum; however, tests for subgroup interaction were non-significant, indicating insufficient evidence to confirm a true difference in effect by formulation type. Improvements were also noted in waist circumference (MD = -1.36 cm; p = 0.003) and liver enzymes. High-certainty evidence supported body weight reduction; moderate-certainty evidence supported reductions in BMI, waist circumference, fat mass, and liver enzymes; low-certainty evidence was found for lipid, glycemic, and inflammatory outcomes. CONCLUSIONS: L. plantarum, particularly in multi-strain formulations, may provide modest yet clinically meaningful benefits in obesity management. Standardized, long-term trials are warranted. REGISTRY AND REGISTRY NUMBER FOR SYSTEMATIC REVIEWS OR META-ANALYSES: The systematic review and meta-analysis were registered on PROSPERO under the ID: CRD420251102722.