For a study, it was determined that microbial enterotypes may influence the favorable effects of whole-grain enriched diets, including body weight regulation. Overweight patients were randomly assigned to ingest either arabinoxylan-oligosaccharides (AXOS) (10.4 g/d) from wheat bran or polyunsaturated fatty acids (PUFA) (3.6 g/d) in a 4-week intervention experiment. In the study, the researchers used a post-hoc analysis to stratify the intervention participants (n=29) based on their baseline Prevotella-to-Bacteroides (P/B) ratios and then used a linear mixed model analysis to determine the impact of this P/B ratio on the differences in weight changes between the intervention arms. Following AXOS consumption (n=15), the high P/B group gained 0.65 kg (95% CI: 0.16; 1.14, P=.009), while the low P/B group lost no weight [0.14 kg (95% CI: 0.67; 0.38, P=.59)]. As a result, there was a difference of 0.79 kg between the P/B groups (95% CI: 1.51;0.08, P=.030). Following PUFA ingestion, there were no differences between the P/B groups (0.61 kg, 95% CI:0.13; 1.35, P=.10). B. cellulosilyticus had the highest positive rank correlation (Kendall’s tau = 0.51, FDR P=.070) with a 4-week weight change on AXOS among Bacteroides species, and this link was further supported by employing supervised classification methods (Random Forest). Researchers were able to determine the predictive effect of Bacteroides species over P/B enterotype in weight gain after a fiber-based diet intervention by ensuring species and strain separation in the human gut microbiota in this post-hoc research. The findings of this pilot study pave the way for further studies of fiber fermentation outputs from Bacteroides species that affect lipid metabolism in the host and have a direct impact on obesity, allowing for more customized therapies to be developed.