What are the recommended schedules for time-restricted eating (TRE)?

Recommended Schedules for Time-Restricted Eating

An 8-hour time-restricted eating window (with 16 hours of fasting) is the most effective schedule for improving weight loss, body fat reduction, and cardiometabolic health parameters. 1

Optimal Time-Restricted Eating Schedules

• An 8-10 hour eating window with 14+ hours of fasting enhances fat loss, reduces oxidative stress, improves cardiovascular endpoints, and decreases glucose and insulin levels 1
• Early time-restricted eating (e.g., eating between 8:00 AM and 4:00 PM) appears to be more beneficial for weight and glycemic endpoints compared to later eating windows 1, 2
• Late time-restricted eating (eating after 4-5 PM) may worsen postprandial glucose levels and β-cell responsiveness or have null effects 1, 2
• Time-restricted eating reduces energy intake, body weight, and total body fat even when individuals are not instructed to change their diet composition 3, 4

Implementation Considerations

• Time-restricted eating involves confining all calorie intake to a consistent interval of less than 12 hours without overtly attempting to reduce calories 5
• The simplicity of not requiring calorie counting makes time-restricted eating appealing and potentially more sustainable for many individuals 4
• In adults undergoing weight loss treatment, an 8-hour time-restricted window was more effective for weight loss, lowering body fat, and reducing diastolic blood pressure compared to a ≥12-hour eating window 1

Physiological Benefits

• Time-restricted eating may improve insulin sensitivity, reduce glycemic excursions, and increase fat oxidation even in the absence of weight loss 1, 6
• The cardiometabolic effects likely result from synchronization of central and peripheral circadian clocks involved in energy expenditure and fat oxidation 1, 7
• Time-restricted eating can reduce systolic and diastolic blood pressure independent of weight loss 6
• Improvements in fasting insulin and insulin resistance have been reported with time-restricted eating protocols 6

Early vs. Late Time-Restricted Eating

• Early time-restricted eating (eating window starting in early morning) appears to have enhanced metabolic benefits, particularly regarding glucose homeostasis 2
• Both early and late time-restricted eating protocols can effectively reduce body weight and improve altered glucose metabolism, lipid profile, inflammation, and blood pressure levels 2
• However, early time-restricted eating might have a further positive impact on improving blood glucose, insulin levels, and insulin resistance 1, 2

Practical Considerations

• Most adolescents and adults naturally prefer eating windows between approximately 11:00 AM and 7:00 PM 1
• Shifting intake earlier in the day may be challenging based on apparent preferred eating windows and social factors 1
• Many people in the USA typically consume food over a 14-16 hour period, which has been linked to poor cardiometabolic health 1
• Eating 12+ hours out of sync with the light-dark cycle can increase three-hour postprandial glucose levels by 15% and induce insulin resistance in just four days 1

Recommended Approach

1. Start with an 8-hour eating window (e.g., 8:00 AM to 4:00 PM or 10:00 AM to 6:00 PM) 1, 3
2. If early time-restricted eating (e.g., 8:00 AM to 4:00 PM) is feasible, prioritize this schedule for optimal metabolic benefits 1, 2
3. If early eating windows are not feasible due to social or work constraints, a midday to early evening window (e.g., 11:00 AM to 7:00 PM) can still provide benefits 1
4. Maintain consistency in the timing of the eating window to help sustain robust circadian rhythms 5
5. Avoid late-night eating, which has been linked to poor cardiometabolic health 1