In Protocol #2, we will select 30 obese pubertal and 30 obese prepubertal subjects with an abnormal cytokine profile (i.e. fibrinogen and/or hsCRP concentration greater than or equal to 2 Standard Deviations (SD) above the mean established in our lab for lean controls in Protocol #1). They will be randomly assigned to either lifestyle intervention (diet/exercise) or diet/exercise plus metformin for 6 months. After the 6 month evaluation the subjects will cross over the treatment arms, i.e., those that were doing diet/exercise intervention only will add metformin, those that were doing the diet/exercise plus metformin will discontinue the metformin and continue with diet/exercise changes only. Intrahepatic fat contents will be measured as well.