To determine if bile acids are directly responsible for the resistance of eNOS-TG mice to diet-induced weight gain, we administered the farnesoid X receptor (FXR) agonist GW4064, which was shown previously to decrease bile acid abundance and promote obesity in C57BL/6J mice (Watanabe et al., 2011). The gene discussed is NR1H4; the disease is obesity due to melanocortin 4 receptor deficiency.