FASN and obesity due to melanocortin 4 receptor deficiency: Similar studies using HFD feeding to generate obesity resulted in increased hepatic expression of genes involved in fatty acid catabolism and ketone body synthesis, such as acyl-CoA oxidase1 (Acox1) and HMG-CoA lyase (Hmgcl), while genes involved in lipogenesis and cholesterol synthesis, such as fatty acid synthase (Fasn) and acetyl-CoA synthetase 2 (Acsl6), were drastically decreased in the HFD group (86).