FGF21 and metabolic dysfunction-associated steatotic liver disease: TNF-α is associated with insulin regulation related to onset and progression of NAFLD.[7] Fibroblast growth factor-21 (FGF-21) and irisin are myokines playing important roles in NAFLD pathogenesis.[8] Irisin is a myokine that increases energy expenditure, ameliorates insulin sensitivity, and stimulates weight loss.