OnDemand: February 2026 Grand Rounds: Host-Diet-Gut Microbiome Interactions-Host-Diet-Gut Microbiome Interactions

Video Transcription

Video Summary

Dr. Karen Corbin presented research on the gut microbiome’s role in energy balance and obesity, arguing that the colon functions as a “human bioreactor” whose microbial products can influence host metabolism. She described a tightly controlled crossover feeding study comparing a Western diet with a high-fiber, resistant-starch “microbiome enhancer” diet. In healthy adults, the microbiome-enhancer diet led to about 116 fewer calories absorbed per day, mainly through increased fecal energy loss rather than changes in energy expenditure. It also altered microbial biomass, short-chain fatty acids, and several metabolites, including lower protein-fermentation products and much higher urolithin A. Some satiety hormones were modestly affected, though appetite and food intake did not clearly change. Corbin emphasized that diet strongly shapes microbial metabolism and that fecal energy absorption may be a key mechanism linking the microbiome to body weight. She closed by outlining next steps: studying people with obesity, measuring microbial biomass more precisely, identifying biomarkers of dietary intake, and testing whether some individuals are more resistant to microbiome-driven changes in energy absorption.

Keywords

gut microbiome

energy balance

obesity

colon microbiome

microbiome enhancer diet

resistant starch

fecal energy loss

short-chain fatty acids

urolithin A