 Nonalcoholic Fatty Liver Disease NAFLD is becoming the most common cause of liver disease in pediatrics, but little is known about its pathophysiology in children. While studies in obese adults with hepatic steatosis have described an increased hepatic de novo lipogenesis DNL depending on the diet, there are no studies exploring the mechanisms by which excess hepatic triglycerides increases in obese youths, thus explaining the accompanying dyslipidemia and the metabolic syndrome. The central hypothesis of this study is that hepatic conversion of carbohydrates to lipid DNL is enhanced and associated with accumulation of excess liver fat, dyslipidemia and hepatic insulin resistance in obese youths with hepatic steatosis. The overall goal is to examine whether hepatic DNL is increased in obese youths with steatosis compared to matched controls without steatosis. 