FGF21 and Insulin resistance: The beneficial roles of FGF21 on metabolism are further validated by several studies using animal models deficient for FGF21 or its cognate receptor, which exhibited increased adiposity, exacerbated hepatic fat accumulation, insulin resistance, and hyperglycemia [14,183,184], suggesting that circulating FGF21 may be increased in patients with NAFLD in order to maintain energy homeostasis under metabolic stress.