1. "Presence of NAFLD": This will be defined by the presence of at least two of the following criteria: (a) suggestion of liver fat by an imaging study (ultrasound, CT scan, MRI or MR spectroscopy) performed in the 6 months prior to enrollment; (b) elevated aminotransferase levels (ALT > 31 U/L for men or > 19 U/L for women, or AST > 30 U/L) on at least two occasions in the 6 months preceding enrollment; and (c) presence of the metabolic syndrome, defined according to the modified AHA/NCEP criteria. Biopsies are not required; however, previous biopsy done within the 6 months prior to the initiation of the study will be considered diagnostic if typical findings of NAFLD are described and other causes of liver disease are ruled out;