Background

The gut microbiota has been shown to change dramatically after bariatric surgery. The goal of this study was to examine the relationship between early changes in the composition of the gut microbiota and the magnitude of subsequent weight loss following RYGB or SG.

Methods

Patients were enrolled across 2 sites in this longitudinal study prior to undergoing a RYGB or SG. Height, weight, and metagenomic shotgun sequencing for microbiome characterization occurred at pre-surgery and at 1, 6, 12 months following surgery. A simple linear model was used to compare the log-normalized abundance of each taxa with time. To determine the relationship between changes in the microbiome and weight, participants were divided into 5 quintiles, with the top and bottom quintiles representing the 20% of patients who lost the most and least weight, respectively, between baseline and 12 months.

Results

At the genus level, 147 taxa were significantly correlated with time post-surgery at a 5% False Discovery Rate (FDR) corrected p-value. Among participants in the top weight loss quintile, 82 taxa were significantly associated with time at a 5% FDR value whereas 22 taxa were significantly associated with the weight loss amount in the bottom 4 quintiles.

Conclusions

The microbial community changes are much more pronounced in patients who have the most dramatic weight loss in the first post-operative year. Future research will examine the relationships between changes in microbiome composition and weight regain.