Randomized controlled trials reporting the effects of probiotics in individuals with overweight and obesity: A critical review of the interventions and body adiposity parameters

Obesity is a complex chronic metabolic disease that impairs health and reduces lifespan. Therefore, effective strategies for the prevention and treatment of obesity are necessary. Although several studies have demonstrated that gut dysbiosis is associated with obesity it, remains controversial whether the altered gut microbiota is a risk factor for or a consequence of obesity. Recent randomized clinical trials (RCTs) evaluating if gut microbiota modulation with probiotics favors weight loss present conflicting results, which can be attributed to the heterogeneity in the study designs. The aim of this paper is to make a comprehensive review describing the heterogeneity of interventions and body adiposity assessment methods of RCTs that evaluated the effects of probiotics on body weight and body adiposity in individuals with overweight and obesity. Thirty-three RCTs were identified through a search strategy. As main results we observed that ∼30% of the RCTs reported a significant decrease in body weight and body mass index (BMI) and ∼50% found a significant reduction in waist circumference and total fat mass. The beneficial effects of probiotics were more consistent in trials with ≥12 weeks, probiotics dose ≥1010 CFU/day, in capsules, sachets or powder, and without concomitant energy restriction. The evidence of probiotics effects on body adiposity may improve and be more consistent in future RCTs which include methodological characteristics such as longer duration, higher dose, non-dairy vehicle, non-concurrent energy restriction and use of more accurate measures of body fat deposits (e.g., body fat mass and waist circumference) instead of body weight and BMI.