The purpose of this study is to see if reducing the number of hours during which one eats each day will help reduce levels of LDL cholesterol and improve other markers of metabolic and cardiovascular health (i.e. blood sugar levels and blood pressure). The study also aims to assess changes in exercise capacity and trimethylamine N-oxide (TMAO) levels in response to Time Restricted Eating (TRE) and Intensive Cardiac Rehabilitation (ICR) versus ICR alone. TMAO is a metabolite, or a substance, produced during digestion and metabolism. Preliminary data illustrates a correlation between high levels of TMAO and higher risk of cardiovascular disease and mortality. We will also be looking at participants' long-term cardiovascular health status after they complete the ICR program.

Inclusion Criteria:

1. Age: 18-75 years
2. Enrollment and planned participation in UC San Diego's 9-week Intensive Cardiac Rehabilitation Program
3. Established diagnosis of coronary artery disease (concomitant systolic or diastolic HF is allowable)
4. Own a smartphone (Apple iOS or Android OS)
5. If patients are on cardiovascular medications (HMG CoA reductase inhibitors (statins), other lipid modifying drugs (including over the counter drugs such as red yeast rice and fish oil), anti-hypertensive, anti-diabetes drugs, no dose adjustments will be allowed during the study period.

Exclusion Criteria:

1. Taking insulin within the last 6 months.
2. Known inflammatory and/or rheumatologic disease.
3. Active tobacco abuse or illicit drug use or history of treatment for alcohol abuse.
4. Pregnant or breast-feeding women.
5. Shift workers with variable (e.g. nocturnal) hours.
6. Caregivers for dependents requiring frequent nocturnal care/sleep interruptions.
7. Planned international travel during study period.
8. Systolic HF alone.
9. Heart transplant within the past 1 year.
10. Presence of left ventricular assist device.
11. Uncontrolled arrhythmia (i.e. rate-controlled atrial fibrillation/atrial flutter are not exclusion criteria).
12. History of thyroid disease requiring dose titration of thyroid replacement medication(s) within the past 3 months (i.e. hypothyroidism on a stable dose of thyroid replacement therapy is not an exclusion).
13. History of adrenal disease.
14. History of malignancy undergoing active treatment, except non-melanoma skin cancer.
15. History of type I diabetes with ongoing insulin dependence.
16. History of eating disorders.
17. History of cirrhosis.
18. History of stage 4 or 5 chronic kidney disease or requiring dialysis.
19. History of HIV/AIDS.
20. Currently enrolled in a weight-loss or weight-management program. This does not include UC San Diego's Cardiac Rehabilitation Programs.
21. On a special or prescribed diet for other reasons (e.g. Celiac disease).
22. Currently taking any medication that is meant for, or has a known effect on, appetite.
23. Any history of surgical intervention for weight management.
24. Uncontrolled psychiatric disorder (including history of hospitalization for psychiatric illness).
25. Baseline eating window <14 hours per day as documented on mCC app.
26. Failure to use the smartphone app for documentation (defined as <2 meals/day for ≥3 days during baseline).