GPT and fatty liver disease: For example, a body mass index (BMI) ≥25 kg/m2 as a measure of overweight or obesity, is not specific for NAFLD, because not all overweight or obese people have fatty liver; and an alanine transaminase (ALT) value > 31U/l in men and >19 IU/l in women is fairly sensitive but is not a specific test for NAFLD[9].