In order to be eligible to participate in this study, an individual must meet all of the following criteria:
- Provision of signed and dated informed consent form.
- Stated willingness to comply with all study procedures and availably for the duration of the study.
- Male or female, age >= 55 years.
- Able to speak and read English. (We do not have ready access to interpreters of different languages at the NIA Clinical Unit).
- BMI >= 27.
- Ability to take oral medication and be willing to adhere to the daily regimen.
- Ability to perform walking and treadmill tests without physical limitations.
- In good general health, as evidenced by medical history/physical exam/laboratory results.
EXCLUSION CRITERIA:
An individual who meets any of the following criteria will be excluded from participation in this study:
- History of diabetes requiring treatment with any glucose lowering drug(s).
- Fasting glucose >= 126 on screening visit.
- Is on treatment with an investigational drug or other intervention within 8 weeks of enrollment.
- Hospitalization within 12 months for myocardial infarction, coronary revascularization or bypass surgery or stroke.
- History of autoimmune disease, e.g., Hashimoto s thyroiditis, Myasthenia Gravis or Rheumatoid Arthritis.
- Uncontrolled thyroid disease.
- Chronic liver disease indicated by medical history or one of the liver enzymes greater than 2 times the normal range.
- History of chronic kidney disease or GFR <60 mL/min/1.73 m\^2.
- Anemia (defined as hemoglobin level <12 g/dl for men or < 11 g/dl for women).
- Poor venous access.
- Uncontrolled hypertension as judged by the Investigator.
- History of significant GI disease, e.g., IBS, Crohn s disease.
- Active cancer or has had treatment for cancer in the last 1 year.
- Medical condition requiring absolute and continuous need for long-term treatment with antibiotics, corticosteroids, immunosuppressors.
- Currently pregnant or a nursing mother due to possible changes in hormones and metabolism.
- History of, or laboratory evidence of HIV virus infection at Screening Visit.
- History of, or laboratory evidence of Hepatitis B or C at Screening Visit.
- Positive urine drug screen at Screening Visit (unless taking prescribed medication and at the discretion of the PI).
- Reports claustrophobia and/or is not eligible to have an MRI as per the MRI eligibility form.
- Weight >= 300 lbs (MRI scanner weight limit).
- Hip or knee replacement or other medical condition that prevents MRI research scans from being performed.
- Diagnosed with cognitive impairment that clearly prevents the participant from providing informed consent.
- Current smoker or tobacco use in the past year.
- History of substance abuse, including marijuana use in the past year.
- On average, consumes more than 1 alcoholic drink per day.
- Any other condition which in the investigator s opinion may adversely affect the subject s ability to complete the study or its measures or which may pose significant risk to the subject.