Bile acids are a family of signaling molecules synthesized in the liver and metabolized by gut bacteria. As metabolites of the intestinal microbiota, bile acids bind to various receptors, and affect the metabolism and immune function of the host, including glucose and lipid metabolism, energy homeostasis, and inflammatory response. Conversely, bile acids also shape the composition of the gut microbiota. Given their critical role in physiological regulation, disrupted bile acid signaling is closely linked to metabolic diseases. Consequently, therapeutic strategies targeting bile acids are increasingly being explored. The size, composition, and function of the bile acid pool can be modulated through direct treatments (e.g., bile acid replacement therapy, administration of bile acid receptor agonists/antagonists) or indirect treatments (e.g., gut microbiota modulation, probiotic supplementation), providing new ideas for preventing and treating metabolic diseases.