Micronutrients & recovery

VLCD increases the microbial metabolic capacity for butyrate fermentation, whereas LSG decreases it, despite no significant change in actual faecal butyrate concentrations for either group.

Dieting (VLCD) trains your gut bacteria to be more efficient at producing butyrate, a beneficial short-chain fatty acid. Surgery (LSG) reduces this efficiency. However, because you aren't eating much fiber, you don't necessarily see more butyrate in your stool.