Non-alcoholic fatty liver disease (NAFLD) has been recognized as a major cause of chronic liver disease in the industrialized world. The prevalence of NAFLD is not only increased in patients with type 2 diabetes, metabolic syndrome, and obesity, but is also associated with more severe forms of the disease, with a significant proportion of subjects developing NAFLD despite having a relatively normal body mass index (BMI), a condition known as non-obese or lean NAFLD.