Exercise-stimulated Muscle Glucose Uptake in Upper Body Obesity

Inclusion Criteria: For the exercise studies of leg glucose uptake - "insulin sensitive" group: * Sedentary, normal weight, premenopausal women. * Sedentary, age-matched normal weight men. * Weight stable for two (2) months prior to study. * Willing to provide written, informed consent. * For the exercise studies of leg glucose uptake - "insulin resistant" group: For the exercise studies of leg glucose uptake - "insulin resistant" group: * Upper body obese (UBO) premenopausal women. * Age-matched upper body obese (UBO) men. * Weight stable for two (2) months prior to study. * Willing to provide written, informed consent. Exclusion Criteria: * Age \< 18 or \> 55 years (premenopausal women and age-matched men). * Use of glucose-lowering agents. * For female subjects: positive pregnancy test at the time of enrollment or study * History of prior upper abdominal surgery such as adjustable gastric banding, pyloroplasty and vagotomy. * Active systemic illness or malignancy. * Symptomatic macrovascular or microvascular disease.