• INCLUSION CRITERIA

Cohort 1

1. Males and females between the ages of 18 to 65
2. BMI 18.5 - 26.9 kg/m^2
3. Subject understands the protocol and provides written, informed consent in addition to a willingness to comply with specified follow-up instructions and evaluations
4. Normotensive, not on medications for hypertension
5. Not on glucose-lowering or lipid-lowing medications
6. Screening labs with baseline HbA1c <5.7%, baseline fasting triglyceride < 150 mg/dL and LDL <100 mg/dL
7. Liver fat <2%

Cohort 2

1. Males and females between the ages of 18 to 65
2. BMI >26 kg/m^2 and <36 kg/m^2
3. Subject understands the protocol and provides written, informed consent in addition to a willingness to comply with specified follow-up instructions and evaluations.
4. Screening labs with baseline HbA1c <= 7.5%, agree to be off or stop oral glucose-lowering medications (metformin), baseline fasting triglyceride < 500 mg/dL and LDL <190 mg/dL, agree to be off or stop oral lipid-lowing medications for 4-10 weeks prior to the inpatient visit.
5. Liver fat <2%

EXCLUSION CRITERIA

1. For women: pregnancy or currently breastfeeding
2. Subjects <18-year-old. This age group has a broad spectrum of hormonal profiles, due to development and puberty, which significantly increases the heterogenicity of the study subjects.
3. Subjects >65-year-old. This age group has significantly increased risk of cardiovascular diseases. To minimize the risk from temporarily suspending lipid- and glucose-lowering medications and stress from serial blood draws, we exclude these individuals.
4. Heavy alcohol user (males with >2 drinks per day or >14 drinks per week; female with >1 drinks per day or >7 drinks per week)
5. Current smoker, or former smoker who quit smoking <15 years ago
6. Subjects with weight changes greater than 20% baseline body weight over the past 3 months
7. Subjects with lactose intolerance unwilling to take lactase
8. Subjects with type 1 diabetes
9. Subjects with hemoglobin <11 g/dL or hematocrit <33%
10. Subjects with abnormal liver function test results
11. Subjects with liver fat >= 2% on abdominal MRI
12. Subjects with a history of pancreatitis, diabetes ketoacidosis, hyperosmolar hyperglycemic state, advanced atherosclerosis, cardiovascular diseases, kidney diseases, or liver diseases
13. Subjects with fat malabsorption including: history of gastrointestinal surgery, pancreatic insufficiency, inflammatory bowel disease, celiac disease, moderate-to-severe irritable bowel syndrome, and pathologic mutations impacting lipoprotein metabolism
14. Subjects on glucocorticoids >1 week (not including topical glucocorticoids)
15. Subjects with HIV
16. Subjects with uncontrolled psychiatric and/or behavioral disorders
17. Subjects taking diabetes medications other than metformin
18. Anticipated surgery during the study period
19. Subjects with severe medication-resistant claustrophobia
20. Subjects who are unwilling to stop medications, vitamins and/or dietary supplements that investigators have requested to be held
21. Subjects participating in any other clinical study without informing investigators
22. Any other reason or clinical condition that the investigators judge would interfere with study participation and/or be unsafe for a participant or staff member