Bifidobacterium lactis IDCC 4301 as a functional probiotic ingredient for body fat management in adults with overweight or obesity: A 12-week randomized, double-blind, placebo-controlled trial

Obesity-related adiposity requires safe nutritional strategies. This 12-week randomized, double-blind, placebo-controlled trial evaluated Bifidobacterium lactis IDCC 4301 (1 × 10 10 CFU/day) for body fat management in adults with a body mass index (BMI) of 25.0–29.9 kg/m 2 . Participants were randomly assigned in a 1:1 ratio to the B. lactis IDCC 4301 or placebo group using block randomization, with the randomization schedule prepared by an independent third party. In the per-protocol population ( n = 97), dual-energy X-ray absorptiometry (DEXA)-measured total fat mass changed by −735.13 ± 974.78 g in the B. lactis IDCC 4301 group and 1126.21 ± 905.79 g in the placebo group, yielding a − 1.86 kg treatment contrast ( p < 0.0001). Supportive secondary outcomes, including total body fat percentage, regional DEXA-derived fat indices, bioelectrical impedance analysis-derived fat mass, visceral fat area, body weight, BMI, waist and hip circumference, generally favored B. lactis IDCC 4301. Diet and physical activity changes did not differ between groups, and no product-related adverse events occurred. These findings may support B. lactis IDCC 4301 as a functional probiotic candidate for body fat management.