Abstract: The present invention provides various biomarkers of fatty liver disease, including steatosis and steatohepatitis. The present invention also provides various methods of using the biomarkers, including methods for diagnosis of fatty liver disease, methods of determining predisposition to fatty liver disease, methods of monitoring progression/regression of fatty liver disease, methods of assessing efficacy of compositions for treating fatty liver disease, methods of screening compositions for activity in modulating biomarkers of fatty liver disease, methods of treating fatty liver disease, as well as other methods based on biomarkers of fatty liver disease.