Despite the marked amelioration of hepatic steatosis, hepatic FASN deficiency in ob/ob mice, but not that in Mc4r-KO mice, exacerbated liver dysfunction, with this effect being associated with hepatic upregulation of gene expression related to ER stress, inflammation, and apoptosis, implicating these processes in the exacerbation of liver dysfunction. Here, FASN is linked to fatty liver disease.