What’s more, some key enzymes involved in HDL metabolism, such as cholesteryl ester transfer protein (CETP), lecithin/cholesterol acyltransferase (LCAT), hepatic lipase (HL) and protein phospholipid transfer protein(PLTP), are changed in people with obesity who have insulin resistance [11]. Here, PLTP is linked to obesity due to melanocortin 4 receptor deficiency.