*8.2.5 Bariatric surgery*

Bariatric surgery can modify gut microbiome and further affect body weight [57, 58]. The mechanisms include reduced caloric intake, reduced gastric emptying, and alterations in gastric acid production and bile acids.

After Roux-en-Y gastric bypass surgery in obese subjects, there is a decrease in Firmicutes-to-Bacteroidetes phyla ratio and an increase in Proteobacteria phylum [57, 58].
