Inclusion Criteria:

• * Age ≥ 65 years;
• * Body Mass Index (BMI \> 25 kg/m2)
• * Normal age-, gender-, and education-adjusted performance on TICS-M (Telephone Interview for Cognitive Status)
• * Responds yes to questions 1 (memory worse), 2 (word finding difficulties) or 3 (planning/organization difficulties) on the Subjective Cognitive Decline Questionnaire
• * Reports onset of cognitive difficulties in past five years
• * Reports they believe they are worse than others their age OR they have talked to a clinician about it.
• * Provides informed consent and willing to be randomized to either intervention group.

Exclusion Criteria:

• * Failure to provide informed consent;
• * Recent History or clinical manifestation of cardiovascular disease, diabetes, cholelithiasis, liver or renal disease, cancer, or progressive, degenerative neurologic disease (e.g., Parkinson's Disease, multiple sclerosis, ALS)
• * Abnormal laboratory markers (e.g., renal or liver abnormalities, elevated potassium levels, or hemoglobin and hematocrit below the lower limit of normal) as determined by study physician.
• * Significant cognitive impairment, defined as a scores below the cutoff for dementia on TICS-M
• * Severe rheumatologic or orthopedic diseases (e.g., awaiting joint replacement, active inflammatory disease);
• * Terminal illness with life expectancy less than 12 months, as determined by a physician;
• * Other significant co-morbid disease (e.g. renal failure on hemodialysis) or severe psychiatric disorder (e.g. bipolar, schizophrenia);
• * Current use of anabolic medications (i.e., growth hormones or testosterone), antidepressant medications, antipsychotic agents, monoamine oxidase inhibitors, anticholinesterase inhibitors (i.e., Aricept), anticoagulant therapies (aspirin use is permitted), or antibiotics;
• * Excessive alcohol use (\>14 drinks per week);
• * History of drug or alcohol abuse (i.e., more than 5 drinks/day for males or more than 4 drinks/day for females);
• * Planning to permanently leave the area in the next year;
• * History of pulmonary disease, pneumonitis or interstitial lung disease;
• * Current smoker or less than 3 years quit;
• * Creatinine clearance \< 30 ml/minute by estimated Glomerular Filtration Rate (eGFR);
• * Fasting \>12 hours per day
• * Actively trying to lose weight by participating in formal weight loss program or significantly restricting calorie intake or weight loss \> 5 lbs in the past month
• * Resting heart rate of \>120 beats per minute, systolic blood pressure \> 180 mmHg or diastolic blood pressure of \> 100 mmHg
• * Unstable angina, heart attack or stroke in the past 3 months
• * Continuous use of supplemental oxygen to manage a chronic pulmonary condition or heart failure
• * Rheumatoid arthritis, Parkinson's disease or currently on dialysis
• * Insulin dependent diabetes mellitus
• * Taking medications that preclude fasting for 16 hours (e.g. must be taken with food at least 12 hours apart)
• * Participating in another clinical trial or has received an investigational product within 30 days prior to screening/enrollment
• * Any condition that in the opinion of the investigator would impair ability to participate in the trial.