The goal of this clinical trial is to learn about the effects of time-restricted eating in patients with history of acute coronary syndrome. The main questions it aims to answer are: 1) Is 10-hr TRE safe and feasible for patients with ACS; 2)What are the impacts of 10-hr TRE on anthropometric measurements, cardiometabolic health and cardiovascular health compared to ad libitum eating in patients with ACS?. Participants will be asked to limit eating duration to 10 hours daily.

Justification: The effects of TRE on humans varies results, with some showing improvements in weight loss, insulin sensitivity, and cardiovascular markers, while others exhibiting no significant changes. TRE studies on metabolically altered individuals especially patients with heart diseases are limited.

Written approval of the study has been obtained from the Universiti Teknologi MARA Ethics Committee before commencement of this study.

The TRES study utilizes an investigator-led, pragmatic, parallel, randomized, single-blinded clinical trial design to evaluate the safety, feasibility, and effectiveness of a 10-hour time-restricted eating (TRE) intervention compared to unrestricted eating in patients diagnosed with acute coronary syndrome. The study aims to assess the impact of TRE on anthropometric measurements, as well as cardiometabolic and cardiovascular health outcomes. The duration of the randomized controlled trial (RCT) spans a period of five weeks. The trial consisted of a baseline period of one week, which was then followed by a four-week intervention phase. The participants will be assigned randomly to either the TRE (Time-Restricted Eating) group or the control group, which involves ad libitum eating. They will be instructed to adhere to their allotted eating duration during the four-week intervention period.

Inclusion Criteria:

• Adult, 18- 65 years old.
• Had history of acute coronary syndrome (ACS)
• Clinically stable
• Self-reported eating window of at least 12 h per day.

Exclusion Criteria:

• Severe obesity (body mass index ≥40 kg m-2).
• Unstable weight in the past three months (gain or lose more than 4 kg of weight).
• Unstable cardiovascular, renal, cardiac, liver, lung, adrenal, or nervous system disease that may compromise study validity.
• Any medications or supplements known to change sleep, circadian rhythms, or metabolism.
• Pregnant or lactating women.
• Perform overnight shift work more than one day/week on average.
• Regularly fasted for more than 15 hours/day or having completed twelve 24-hr fasts within the past three months).
• Active use of tobacco or illicit drug or history of treatment for alcohol abuse.
• Type I diabetes or diabetic, treated with insulin.
• Use of anti-obesity drugs or other drugs affecting body weight.
• Currently enrolled in weight loss or management programme, including surgical intervention.
• Severe kidney failure (glomerular filtration rate (GFR) <30 mL/min).
• Eating disorder or current diagnosis of uncontrolled psychiatric illness, which may impair study involvement.
• Malignancy undergoing active treatment.
• Had gastrointestinal surgery or impaired nutrient absorption.
• Travelled more than two time zones away two months prior to enrolling in the trial or will travel more than two time zones away during the study period.
• Concurrent participation in other interventional studies