Those with elevated serum ALT without other explanations and with imaging suggestive of fatty liver and with metabolic syndrome-related components have liver enzyme abnormalities of NAFLD as the most likely cause. Factors excluding NAFLD: 1. excessive alcohol consumption: >50 g of ethanol per day (350 g/week), consider alcoholic liver injury; 2. recent use of drugs (including herbal medicines) associated with increased serum ALT and GGT and/or fatty liver; 3. various common (hepatitis B, C) and rare (autoimmune, Wilson disease, a1-antitrypsin deficiency) liver diseases; 4, liver malignancies, infections, biliary tract diseases; 5, for serum HBV DNA 90 cm (men), >80 cm (women), and/or BMI ≥25 kg/m2 (regardless of gender); 2, increased TG: ≥1.7 mmol/L; 3, decreased HDL-C: <1.03 (men).