Overexpression of Cyp7a1, a rate-limiting enzyme in the classic pathway, attenuates weight gain on an HFD and improves metabolic health, including protecting against hepatic steatosis.57 Consistent with this, HCR rats and exercise upregulate Cyp7a1 expression, suggesting a potential role for the classic pathway in preventing and treating hepatic steatosis. The gene discussed is CYP7A1; the disease is fatty liver disease.