The purpose of this study is to examine the effects of consumption of sugar-sweetened beverages on blood triglycerides and cholesterol, cholesterol concentrations, and the body's sensitivity to insulin.

The study is designed as a prospective, blinded diet intervention study during which the participants consume either fructose- or HFCS-sweetened beverages (providing 10%, 17.5% or 25% of energy) with meals. In addition, there will be two control groups, with one group consuming 0% sugar beverages sweetened with sucralose and the other consuming glucose-sweetened beverages at 25% of energy requirement. Experimental procedures, including 24-hour serial blood sampling, post-heparin infusions, gluteal biopsies, Magnetic Resonance Imaging of the liver and the abdomen, and Oral Glucose Tolerance and Disposal Tests, are performed during baseline and at the end of a 2-week intervention period at the UC Davis Clinical and Translational Science Center (CTSC) Clinical Research Center (CCRC). During the inpatient periods, subjects are served energy balanced diets. The diets provide 15% of energy as protein, 30% as fat, and 55% as carbohydrate. During baseline testing, the carbohydrate content consists primarily of complex carbohydrate (>97%). During intervention the 55% carbohydrate will consist of 10% sugar/45% complex, 17.5% sugar/37.5% complex, or 25% sugar/30% complex depending on the diet group to which the subject is assigned. During the outpatient intervention periods, the subjects reside at home and are provided with fructose- or HFCS -sweetened beverages that are consumed with each meal along with a self-selected ad libitum (usual) diet.

Inclusion Criteria:

• Body mass index between 18-35
• Self report of stable body weight during the past six months

Exclusion Criteria:

• Diabetes Mellitus
• Evidence of liver disorder
• Evidence of kidney disorder
• Evidence of thyroid disorder
• Systolic blood pressure consistently over 160mmHg or diastolic blood pressure over 900mmHg
• Triglycerides > 400mg/dl
• LDL-C > 240mg/dl
• Hemoglobin < 8.5 g/dl
• Current, prior (within 2 months), or anticipated use of any hypolipidemic or anti-diabetic agents
• Use of Selective Serotonin Reuptake Inhibitors and anti-hypertensive medications
• Any other condition that, in the opinion of the investigators, would put subject at risk
• Strenuous exerciser
• Pregnant or lactating women
• Smoker
• Diet exclusions: food allergies, special dietary restrictions, habitual ingest of >2 alcoholic beverages/day