Gut microbiota and metabolic responses to a 12-week caloric restriction combined with strength and HIIT training in patients with obesity: a randomized trial.

Background: Nowadays, obesity has become a major health issue. In addition to negatively affecting body composition and metabolic health, recent evidence shows unfavorable shifts in gut microbiota in individuals with obesity. However, the effects of weight loss on gut microbes and metabolites remain controversial. Therefore, the purpose of this study was to investigate the effects of a 12-week program on gut microbiota and metabolic health in patients with obesity.

Methods: We conducted a controlled trial in 23 male and female patients with obesity. Twelve participants completed a 12-week program of caloric restriction combined with strength and HIIT training (INT, pre-BMI 37.33 ± 6.57 kg/m), and eleven participants were designated as non-intervention controls (pre-BMI 38.65 ± 8.07 kg/m). Metagenomic sequencing of the V3-V4 region of the 16S rDNA gene from fecal samples allowed for gut microbiota classification. Nuclear magnetic resonance spectroscopy characterized selected serum and fecal metabolite concentrations.

Results: Within INT, we observed a significant improvement in body composition; a significant decrease in liver enzymes (AST, ALT, and GMT); a significant increase in the relative abundance of the commensal bacteria (e.g., Akkermansia muciniphila, Parabacteroides merdae, and Phocaeicola vulgatus); and a significant decrease in the relative abundance of SCFA-producing bacteria (e.g., the genera Butyrivibrio, Coprococcus, and Blautia). In addition, significant correlations were found between gut microbes, body composition, metabolic health biomarkers, and SCFAs. Notably, the Random Forest Machine Learning analysis identified predictors (Butyrivibrio fibrisolvens, Blautia caecimuris, Coprococcus comes, and waist circumference) with a moderate ability to discriminate between INT subjects pre- and post-intervention.

Conclusions: Our results indicate that a 12-week caloric restriction combined with strength and HIIT training positively influences body composition, metabolic health biomarkers, gut microbiota, and microbial metabolites, demonstrating significant correlations among these variables. We observed a significant increase in the relative abundance of bacteria linked to obesity, e.g., Akkermansia muciniphila. Additionally, our study contributes to the ongoing debate about the role of SCFAs in obesity, as we observed a significant decrease in SCFA producers after a 12-week program.

Trial Registration: The trial was registered on [05/12/2014] with ClinicalTrials.gov (No: NCT02325804).