CYP1B1 and obesity due to melanocortin 4 receptor deficiency: Studies have shown that the activation of AhR induced obesity (Kerley-Hamilton et al., 2012), It may be because the aryl hydrocarbon receptor repressor (AhRR) was significantly down-regulated in obese populations, while AhR and CYP1B1 are significantly upregulated, indicating that AhRR may regulate obesity by inhibiting AhR expression through the AhR-CYP1B1 axis (Shahin et al., 2020).