This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. This study is to find out if the drug metformin (Glucophage XR, Bristol -Myers Squibb Co. Inc) will help obese, non-diabetic adolescents lose weight. We will find this out by comparing one group of subjects that will take metformin to another group who will not take the drug.