Gut bacteria influence the host's metabolism by producing short-chain fatty acids (SCFAs) by fermenting non-digestible carbohydrates. Anorexia patients' gut microbiomes have been shown to have lower-than-normal levels of carbohydrate-fermenting taxa in the Firmicutes phylum like Roseburia, Clostridium, and Eubacterium species. SCFAs like acetate, butyrate, and propionate help to regulate gut homeostasis and influence the host's energy metabolism and appetite by changing the amount of feeding hormones produced by the intestine. Fecal levels of SCFAs, especially butyrate, are lower in anorexia patients than in healthy controls, and these reductions are associated with greater depression and anxiety comorbid symptomatology.