Inclusion Criteria:

   - Subjects must be between the ages of 13.00 and 17.99 at week 0 (Baseline).

   - Subjects must have a BMI ≥ 95th percentile for age and gender using the CDC data (see
   Appendix), but must weigh less than 300 pounds (<136 kilograms) when measured during
   the initial physical exam at week 0 (Baseline). BMI will be calculated as follows;
   weight in kilograms  [height in meters]2. This cutoff has been established due to the
   weight-bearing limits of the table used in performing the DXA scan. Once enrolled, if
   a subject's weight progresses above 300 pounds, s/he may continue in the study whether
   it is possible to perform DXA or not.

   - Completion of informed consent/assent process

Exclusion Criteria:

   - Known diabetes as defined by the American Diabetes Association criteria

   - Prior drug therapy to treat diabetes or insulin insensitivity, including any form of
   insulin or insulin analogs; or any oral antidiabetic medication; acarbose,
   acetohexamide, chlorpropamide, glimepiride, glipizide, glyburide, metformin,
   pioglitazone, repaglinide, rosiglitazone, tolazamide, tolbutamide or troglitazone.

   - Prior use of drugs to aid in weight loss, including but not limited to: Benzphetamine
   Hcl, Diethylpropion Hcl, Fenfluramine Hcl, Phendimetrazine Tartrate, Phentermine Hcl,
   Orlistat, Sibutramine Hcl Monohydrate, Didrex, Tenuate, Pondimin, Bontril-SR,
   Adipex-P, Fastin, Ionamin, Phentrol, Xenical, Meridia.

   - Subject is currently taking the following medications at the time of the Screening
   visit: Cimetidine, amiloride, digoxin, furosemide, morphine, nifedipine, procainamide,
   ranitidine, triamterene, trimethoprim, vancomycin and quinidine, as these medications
   may increase metformin levels.

   - Subjects will be excluded from the study if they have taken prescription-strength
   glucocorticoids (by any route) within three months of the screening visit. Topical
   glucocorticoids are acceptable if their strength is no greater than the equivalent of
   1% hydrocortisone cream.

   - History of any syndrome or medical disorder associated with significant obesity,
   including but not limited to: Prader Willi Syndrome, Bardet-Biedl Syndrome, Cohen
   Syndrome, Cushing syndrome or disease.

   - Prior surgical therapy for obesity

   - Subject to be excluded if s/he has attended a formal weight loss program within 6
   months prior to the Screening visit.

   - In the 6 months prior to Screening, subject has consumed alcohol more frequently than
   twice per week and/or subject has had more than three alcohol-containing beverages in
   a 24 hour period.

   - Elevated creatinine (> 1.2 mg/dl)

   - Untreated disorders of thyroid function

   - Elevated liver enzymes (Alanine Aminotransferase [ALT] or Aspartate Aminotransferase
   [AST]) > 80 (approximately 2 times upper limit of normal)

   - Mobility impairment that prevents full participation in recommended physical activity

   - Other serious medical condition that the Principal Investigator or Lead Site
   Investigator determines may put the patient at undue risk if enrolled in the study

   - Unable to comply with the protocol in the opinion of the Principal Investigator or the
   Lead Site Investigator

   - Subjects with child-bearing potential who are unwilling to remain abstinent or use an
   effective method of birth control

   - Previous pregnancy