The purpose of the study is to examine whether a medication called acipimox can improve your body's mitochondria. Mitochondria are the "power house" of the cell and make energy for your body.

Obesity is associated with increased risk for developing diabetes. However, the investigators do not know how obesity leads to diabetes. Previous studies have shown levels of fat in the blood (free fatty acids or FFA) are higher in obesity, and elevated FFA can affect how our body uses glucose and responds to insulin. Recent studies have shown that changes in mitochondria may be involved in the development of diabetes and may be affected by FFA. The investigators propose to improve the function of mitochondria in obese people with pre-diabetes by treating with acipimox, a medication which decreases FFA. The investigators will use state of the art techniques to evaluate the mitochondria, including a new magnetic resonance imaging (MRI) technique to measure function of mitochondria in muscle.

Inclusion Criteria:

1. Men and women age 18-55 years old
2. Body Mass Index (BMI) ≥ 30 kg/m2
3. Waist circumference ≥ 102 cm in men and ≥ 88 cm in women
4. Hypertriglyceridemia defined as triglycerides ≥ 150 mg/dl OR Insulin resistance defined as elevated fasting glucose (≥ 100 mg/dl but <125 mg/dl) or hyperinsulinemia defined as fasting serum insulin ≥ 10 uU/ml.

Exclusion Criteria:

1. Subjects on any hormonal treatment including estrogen, hormone replacement therapy, oral contraceptives, testosterone, glucocorticoids, anabolic steroids, GH, GH releasing hormone or Insulin like growth factor (IGF)-1 within 3months of enrollment.
2. Subjects who have a known history of diabetes, using any anti-diabetic drugs, or fasting blood glucose of ≥ 125 mg/dl.
3. Use of cholesterol lowering medication including niacin or fish oil.
4. Changes in anti-hypertensive regimen within 3months of screening.
5. Chronic illness including HIV, anemia (Hgb <12 g/dL), chronic kidney disease (Creatinine > 2 mg/dL), or liver disease (SGOT > 2.5 x upper limit normal).
6. Use of Aspirin, Clopidogrel (Plavix), Warfarin (Coumadin) or other anti-coagulants
7. History of or active peptic ulcer disease
8. History of any recent cardiovascular event including myocardial infarction (MI; heart attack), cerebral vascular accident (CVA; or stroke) or transient ischemic attack (TIA; or mini-stroke) within 3 months of screening visit, unstable angina pectoris, oxygen-dependent severe pulmonary disease
9. Subjects with contraindication for an MRI study including any significant metal in their body including surgical clippings, or pacemakers and known claustrophobia.
10. History of recent alcohol or substance abuse (< 1 year)
11. Positive pregnancy test or lactating females
12. Women of child-bearing potential not currently using non-hormonal birth control methods including barrier methods (intra-uterine device or IUD, condoms, diaphragms) or abstinence
13. Subject is currently enrolled in another investigational device or drug trial(s), or subject has received other investigational agent(s) within 28 days of baseline visit.

6 months