Healthy overweight/obese individuals will be screened for insulin resistance. Both insulin resistant individuals and insulin sensitive individuals (to serve as controls) will be eligible to enroll. Fat cel biopsy and CT scan of the abdomen is required at baseline and after an intervention with either weight loss or pioglitazone (drug to improve insulin resistance). Subjects will repeat insulin resistance test after the intervention as well. Subjects will learn much about their metabolism in this study, and will have an opportunity to improve their insulin resistance.