FGF21 and Obesity: Circulating FGF-21 levels are elevated in individuals with NAFLD and FGF-21 levels correlated with BMI positively in people with overweight and obesity.[11] Correlations between FGF-21 levels and BMI, waist circumference, and visceral adipose tissues, proposing that obesity is an FGF-21 resistance condition.[35] In this study, FGF-21 levels decreased significantly (P = .002).