In this report, we have shown that UDCA reverses obesity-reduced SIRT1, PGC1α, and Tfam expression, that also increased mitochondria complex I, II, V mRNA expression in ob/ob mice, suggesting UDCA is a potential agent to promote mitochondrial biogenesis and improved mitochondrial function. The gene discussed is PPARGC1A; the disease is obesity due to melanocortin 4 receptor deficiency.