We found that highly enriched UDCA enhances de novo BA and cholesterol synthesis via induction of several BA and cholesterol synthetic markers and enzymes such as C4, 7α-hydroxycholesterol and CYP7A1 (for BAs) and hepatic SREBP2 and HMGCR (for cholesterol) in morbid obesity. The gene discussed is HMGCR; the disease is morbid obesity.