Early TRF (eTRF): Exploring the Optimal Window for Time-Restricted Feeding

Discover the intriguing findings from a recent study on "early time-restricted feeding" (eTRF) in this comprehensive article. Explore how shifting your eating window earlier in the day may impact glucose levels, circadian rhythms, and gene expression, while considering the potential benefits and unanswered questions surrounding this dietary approach.

What is Early TRF? 

Time-restricted feeding (TRF) has gained significant attention in the wellness community, and a recent study has shed light on an interesting aspect of this dietary approach. Known as "early TRF" or eTRF, this strategy involves shifting the feeding window earlier in the day. In a controlled study, participants followed an eTRF protocol where they consumed their meals between 8 am and 2 pm, while the control group adhered to a feeding window between 8 am and 8 pm.

The study, although small and short-term, yielded intriguing results. Participants in the eTRF group showed lower 24-hour glucose levels compared to the control group. Notably, the eTRF group experienced lower mean glucose levels during sleep, indicating potential benefits for nighttime glucose regulation. Additionally, eTRF reduced glucose excursions and lowered insulin levels compared to the control group.

Effects on circadian rhythm

One interesting finding was the impact of eTRF on circadian rhythm. Morning cortisol levels tended to increase, while evening levels decreased in the eTRF group, suggesting an improvement in circadian rhythm. This may help explain the lower glucose levels observed during sleep in this group. However, it's worth noting that the measurement of cortisol in the blood provides an incomplete picture, and further investigation using urine samples may yield more accurate results.

Moreover, the study discovered that eTRF induced significant changes in circadian clock gene expression. Specifically, the eTRF group exhibited increased expression of the autophagy gene LC3A and the SIRT1 gene, both of which are associated with cellular repair and longevity. These findings are of particular interest, as both the eTRF and control groups consumed the same types and amounts of meals during the study.


While this study has limitations, including its small sample size and short duration, it provides valuable insights into the potential benefits of eTRF. The findings suggest that avoiding food for several hours before bed may help regulate nighttime cortisol, glucose levels, and possibly improve sleep quality. However, it remains unclear whether different feeding windows, such as eating between 11 am and 5 pm, would yield similar or more optimal results compared to the 2 pm dinnertime protocol.

Future research should explore various feeding windows to determine the most effective and sustainable approach to TRF. Investigating the impact of different fasting and feeding durations on gene expression, hormonal responses, and metabolic markers would provide a more comprehensive understanding of the optimal window for TRF. As more studies uncover the potential benefits of TRF, it becomes increasingly important to refine and personalize dietary recommendations to maximize individual health outcomes.

Disclaimer: The information provided in this article is for educational purposes only and does not constitute medical advice. It is recommended to consult with a healthcare professional before making any significant changes to your diet or lifestyle.

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