Inclusion Criteria:

• * Metabolically healthy lean subjects must have a body mass index (BMI) 18.5-24.9 kg/m2, intrahepatic triglyceride (IHTG) content ≤5%, serum triglyceride (TG) concentration \<150 mg/dl, fasting plasma glucose concentration \<100 mg/dl, 2-hr oral glucose tolerance test (OGTT) plasma glucose concentration ≤140 mg/dl, and hemoglobin A1C (HbA1C) ≤5.6%.
• * Metabolically healthy obese subjects must have a BMI 30-49.9 kg/m2; IHTG content ≤5%, serum TG concentration \<150 mg/dl, fasting plasma glucose concentration \<100 mg/dl, 2-hr OGTT plasma glucose concentration ≤140 mg/dl, and HbA1C ≤5.6%.
• * Metabolically unhealthy obese subjects must have a BMI 30-49.9 kg/m2; IHTG content ≥5.6% and fasting plasma glucose concentration ≥100 mg/dl or 2-hr OGTT plasma glucose concentration ≥140 mg/dl or HbA1C ≥5.7%.

Exclusion Criteria:

• * medical, surgical, or biological menopause;
• * previous bariatric surgery where the gastrointestinal tract is reconstructed such as Roux-en-Y, sleeve gastrectomy and biliopancreatic diversion surgeries;
• * laparoscopic adjustable gastric band (lab band) surgery within the last 3 years;
• * structured exercise ≥250 min per week (e.g., brisk walking);
• * unstable weight (\>4% change during the last 2 months before entering the study);
• * significant organ system dysfunction (e.g., diabetes requiring medications, severe pulmonary, kidney or cardiovascular disease);
• * cancer or cancer that has been in remission for \<5 years;
• * polycystic ovary syndrome;
• * major psychiatric illness;
• * conditions that render subject unable to complete all testing procedures (e.g., severe ambulatory impairments, limb amputations, or metal implants that interfere with imaging procedures; coagulation disorders);
• * severe anemia;
• * regular use of tobacco products;
• * excessive consumption of alcohol (≥3 drinks/day for men and ≥2 drinks/day for women);
• * use of medications that are known to affect the study outcome measures (e.g., steroids, non-statin lipid-lowering medications) or increase the risk of study procedures (e.g., anticoagulants) and that cannot be temporarily discontinued for this study;
• * use of antibiotics in last 60 days;
• * pregnant or lactating women;
• * vegans, vegetarians, those with lactose intolerance and/or severe aversions/sensitivities to eggs, fish, nuts, wheat and soy, and/or any individuals with food allergies that induce an anaphylactic response;
• * persons who are not able to grant voluntary informed consent