Ability of Hypocaloric Diets to Change Nutrient–Phyla Associations after 8 Weeks of Intervention

Background: Previous studies have suggested that changes in the composition of intestinal microbiota may be influenced by dietary quality. Objective: This study aimed to assess the impact of a hypocaloric diet on the relationship between microbiota and clinical/dietary variables. Methods: This was a longitudinal study. Ten women with obesity (Obese Group, ObG) participated in an 8-week home-based hypocaloric diet intervention. Anthropometric, dietary intake, biochemical, and gut microbiota assessments were conducted before and after the intervention. Microbiota relative abundance was determined using real-time PCR in triplicate. Results: In the ObG, the hypocaloric diet intervention led to significant weight loss (before: 119.5 ± 10.3 kg; after: 114.9 ± 10.2 kg; p = 0.003). Following the intervention, positive correlations were observed between nutrient intake and phyla composition: Actinobacteria phylum with fibers (r = 0.787; p = 0.012), Firmicutes phylum with proteins (r = 0.736; p = 0.024), and Proteobacteria phylum with lipids (r = 0.669; p = 0.049). Conclusions: The hypocaloric diet intervention improved health parameters associated with obesity and its comorbidities, demonstrating associations between nutrient intake and specific phyla.