While the Tomlinson laboratory worked on identifying the role of the AHR in obesity during the 2010s, the concurrent implication of the AHR in the physiological regulation of energy metabolism by the Xie and Tischkau laboratories in the early 2010s also led to a surge of interest into further teasing out the metabolic gene pathways that the AHR regulates in the absence of toxicants. The gene discussed is AHR; the disease is obesity due to melanocortin 4 receptor deficiency.