Effect of Diet Composition on Liver Fat and Glucose Metabolism

Inclusion Criteria: * Age 18-55 years old, men and women, otherwise in good general health, BMI \>27 kg/m2 Exclusion Criteria: * Abnormal glucose tolerance, fasting glucose\>100 mg/dl or diabetes * History of liver condition or alanine aminotransferase (ALT) above the upper limit of the normal range * Use of medications that cause insulin resistance or fatty liver: niacin, glucocorticoids, estrogens, tamoxifen, amiodarone, accutane, sertraline, atypical antipsychotics, anti-HIV medications * Chronic use of anti-inflammatory medications (aspirin, ibuprofen, naprosyn, steroids, etc) * Average alcohol intake \>20 grams/day * Tobacco use * Creatinine \>1.5 mg/dl for men and \>1.4 mg/dl for women * Hematocrit \<33% * Pregnancy or lactation * Significant weight loss within the past 6 months (\>5% body weight) * Claustrophobia or any contraindications to being placed in the magnet for the MRS scan such as pacemakers, defibrillators, brain aneurysm clips, etc. * Other serious medical conditions or inflammatory conditions such as cancer, inflammatory arthritis, etc. * History of multiple food allergies or intolerances or severe food allergies * History of coronary artery disease, history of or treatment of hyperlipidemia, LDL \>200 mg/dl, fasting triglycerides \>300 mg/dl * Weight \>300 pounds