 - Concurrent use of medications that may alter metabolic parameters including metformin, sulfonylurea agents, thiazolidinediones, weight loss agents, androgens or systemic glucocorticoids; lipid-lowering agents and oral contraceptives will be permitted as long as formulations, dosages and adherence remain unchanged throughout the course of the study. Oral contraceptives that are started during the course of the study will require the subject to be withdrawn from the study 