FGF21 and obesity due to melanocortin 4 receptor deficiency: Consistent with a protective role, endogenous FGF21 serum concentration may be elevated by up to 10–20-fold in patients with NAFLD (62, 63), NASH (64), obesity (64–66), type 2 diabetes (67), chronic kidney disease (68), diabetic nephropathy (69), atherosclerosis (70, 71), or coronary heart disease (72).