The main purpose of the clinical trial is to determine the health impact of a dietary intervention known as time-restricted eating (TRE) in patients with metabolic syndrome (defined as the presence of elevated fasting plasma glucose and two or more of the following criteria: increased waist circumference, elevated fasting plasma triglycerides, reduced high-density lipoprotein-cholesterol, elevated blood pressure) and self-reported dietary intake of ≥14 hours per day. Participants will reduce the amount of time they eat to 10 hours per day over a 12-week monitored intervention followed by a 12-week self-directed intervention and will log their dietary intake using a smartphone application (myCircadianClock (mCC) app). Glucose homeostasis (blood glucose levels will be monitored continuously for 2 weeks at the baseline, at the end of the monitored intervention, and at the end of the self-directed intervention using a continuous glucose monitor), and other metabolic, neuroendocrine, inflammatory and oxidative stress/antioxidant defense biomarkers, body weight and composition, blood pressure, heart rate, sleep and activity (using mCC app), personal sense of wellness and dietary timing (using health questionnaires) will be evaluated at the baseline, at the end of the monitored intervention, and at the end of the self-directed intervention.

Metabolic syndrome occurs in approximately 30% of adults and is associated with increased risk of cardiovascular disease and type 2 diabetes. Circadian rhythm disruption due to lifestyle including erratic eating patterns may lead to metabolic and neuroendocrine dysfunction, inflammation, oxidative stress, and cardiometabolic diseases. Maintaining a daily rhythm of eating and fasting cycles sustains a robust circadian rhythm which improves cellular bioenergetics and metabolism. Recent studies support the notion that restricting a period of food intake to 8-12 hours a day (time-restricted eating, TRE) can prevent and reverse obesity and metabolic dysfunction.

The main purpose of the clinical trial is to determine the health impact of TRE in patients with metabolic syndrome (defined as the presence of elevated fasting plasma glucose and two or more of the following criteria: increased waist circumference, elevated fasting plasma triglycerides, reduced high-density lipoprotein-cholesterol, elevated blood pressure) and self-reported dietary intake of ≥14 hours per day. Participants will reduce the amount of time they eat to 10 hours per day over a 12-week monitored intervention followed by a 12-week self-directed intervention and will log their dietary intake using a smartphone application (myCircadianClock (mCC) app, developed by the Salk Institute for Biological Studies). The participants will select a 10-h eating window that best suits their lifestyle. All food/beverages except water must be consumed within the time-interval. No further dietary restrictions will be applied. The participants will be provided with behavioral nutritional counseling by a dietician. Glucose homeostasis (blood glucose levels will be monitored continuously for 2 weeks at the baseline, at the end of the monitored intervention, and at the end of the self-directed intervention using a continuous glucose monitor), and other metabolic, neuroendocrine, inflammatory and oxidative stress/antioxidant defense biomarkers, body weight and composition, blood pressure, heart rate, sleep and activity (using mCC app), personal sense of wellness and dietary timing (using health questionnaires) will be evaluated at the baseline, at the end of the monitored intervention, and at the end of the self-directed intervention. The investigators will assess for compliance with TRE using mCC app.

Inclusion Criteria:

1. Metabolic syndrome, defined as the presence of elevated fasting plasma glucose ≥ 100 mg/dL and two or more of the following criteria:

   Elevated waist circumference: ≥ 102 cm in men, ≥ 88 cm in women; Fasting plasma triglycerides ≥ 150 mg/dL (or on drug treatment for elevated triglycerides); Reduced High-density lipoprotein (HDL)-cholesterol < 40 mg/dL in men, < 50 mg/dL in women (or drug treatment for reduced HDL-cholesterol); Elevated blood pressure, Systolic blood pressure ≥ 130 mm Hg and/or diastolic blood pressure ≥ 85 mm Hg (or drug treatment for hypertension).

2. BMI > 25

3. Duration of eating period ≥ 14 hours/day.

4. Own a Smartphone with Apple Operating System (OS) or Android OS.

Exclusion Criteria:

1. Diagnosis of diabetes.
2. Pregnant or lactating women.
3. Active smoking or illicit drug use or history of treatment for alcohol abuse.
4. Shift work.
5. Caregivers for dependent requiring nocturnal care.
6. Planned travel over time zones during the study period.
7. History of major adverse cardiovascular event within the past 1 year (acute coronary syndrome, percutaneous coronary intervention, coronary artery bypass graft surgery, hospitalization for congestive heart failure, stroke/transient ischemic attack) or current uncontrolled arrhythmia.
8. Uncontrolled medical conditions due to rheumatologic, hematologic, oncologic, infectious, gastrointestinal, psychiatric, nephrological, or endocrine diseases.
9. Known history of an eating disorder.
10. Currently enrolled in a weight-loss or weight-management program.
11. Special or prescribed diet for other reasons (e.g. Celiac disease).
12. Current treatment with antidepressants, medications affecting appetite, or immunosuppression.
13. History of bariatric surgery.
14. A score of > 16 on the Epworth Sleepiness Scale.
15. Depression determined by the Beck Depression Inventory.
16. Failure to use the smartphone app for documentation during a 2-week baseline period.