CLOCK and obesity due to melanocortin 4 receptor deficiency: There is strong evidence that alterations to the hepatic circadian clock increase the risk of developing nonalcoholic liver disease, obesity, and metabolic defects (Molusky et al. 2012, Reinke & Asher 2016, Mayeuf-Louchart et al. 2017, Shi et al. 2019).