What are the Health Benefits of Time Restricted Eating?

by Rob Siabanis MS, RDNLifestyle
Clock on a plate surrounded by foods

Introduction

People will take myriad paths on the road to health and wellness, as evidenced by the slew of competing diet regimens, meal plans, and wellness programs on the Internet. Controversy, confusion, and doubt abound as people try to navigate this jungle of conflicting information. It is rare for one diet recommendation to be effective, evidence-based, and even compatible with most existing diet programs. Time-restricted eating (TRE) might be that lifestyle change that is simple in principle, compatible for most individuals, and most importantly, it seems to work. This article will cover what time-restricted eating is, its benefits, safety concerns, and simple ways to transition into TRE.

What is TRE?

TRE is a form of daily fasting where eating takes place for a limited number of hours. Some use the term Time-Restricted Feeding (TRF), but this is often used when referring to lab animals, such as mice and rats, which scientists feed. TRE practitioners will usually limit their meals to an 8-12 hour window, referred to as the eating window. The main idea behind TRE is that for millions of years, plants and animals have evolved with the cycles of light and dark, day and night. Our metabolism, the chemical processes in our cells that sustain us, appears to follow this daily cycle. For example, the hormone melatonin is produced at night, nudging us to go to bed, and its production ceases with the light of dawn. TRE proponents argue that aligning our meals with these daily cycles will improve our metabolism because our bodies will be better able to utilize the food we eat.

What are the health benefits of TRE?

The rationale behind TRE makes sense on paper, but does the science support it? Scientists have observed for decades that the timing of meals can significantly affect one’s body, indicating that there are health benefits of TRE. For example, in a study dating back to 1975, researchers observed that the same meal was more fattening when consumed at night instead of in the morning (1). Other studies have supported this finding showing that when individuals eat most of their calories during breakfast and lunch, their glucose metabolism improves (2), and they lose weight (3). But in these studies, the eating window was not limited; the volunteers just ate less food at night. Researchers wanted to explore whether restricting eating to a specific time frame provides additional health benefits. In one study, those who adopted an early 8-hour eating window (8:00 am-3:00 pm) for five weeks significantly reduced their blood sugar, insulin, blood pressure, and oxidative stress. Both groups were eating the same diet, so it was the timing of meals that caused this powerful metabolic effect (4). More studies have found that TRE can improve additional metabolic markers, such as total cholesterol (5) and triglycerides (6), which are key indicators of heart health. While the exact metabolic changes differ between studies (7, 8), there appears to be a marked improvement in most individuals who adopt TRE for a few weeks.

Is TRE safe?

Fortunately, adopting TRE appears to be safe for most individuals. In all of the studies included above, the participants complied with the eating window and did not report any significant side effects. However, there appears to be a marked difference between early TRE and late TRE. One study compared the effects of eating three separate meals during the day or eating all the day’s meals in a 4-hour window at night. Eating a heavy meal before bedtime was detrimental to the participant’s metabolism, resulting in increased blood lipids, insulin, and blood pressure (9). This is not surprising since humans have evolved to eat while there is light and sleep when it’s dark. Eating late at night can also lead to impaired sleep quality, which is associated with an increased risk of premature death (10), and dementia (11). Therefore, to maximize safety and effectiveness while practicing TRE, try shifting the eating window as early as possible, allowing your body to process food at its peak.

How can I get started?

TRE is quite simple to implement into your current lifestyle because it doesn’t require you to change your everyday diet. You can first gauge your current average eating window and gradually implement TRE. For example, if you are currently on a 14-hour eating window (07:00 am-09:00 pm), you can start with a 12-hour window (07:00 am-07:00 pm). Shifting your breakfast forward is also possible, making the transition to a 10-hour window (08:00 am-06:00 pm) more realistic, especially if you frequently have social dinners. It’s essential to find something that works for your lifestyle. Even the “perfect” TRE protocol is ineffective if not practiced consistently. If you shift the eating window forward, try to “front-load” your calories earlier in the day, which will give you a metabolic advantage and improve your sleep quality.

Conclusion

In the confusing and conflicting space of nutrition and wellness, TRE is a breath of fresh air in its simplicity, scientific soundness, and compatibility with most lifestyles. While there is much to learn about the exact benefits and mechanisms behind TRE, it appears to be a safe and effective way to improve health and wellbeing without making any radical changes.

References

  1. Hirsch, E., et al., (1975). Chronobiologia 2(suppl. 1):31–32.
  2. Morris CJ, et al., (2015). doi:10.1002/oby.21189
  3. Jakubowicz D, et al., (2013). doi:10.1002/oby.20460
  4. Sutton EF, et al., (2018). doi:10.1016/j.cmet.2018.04.010
  5. Wilkinson MJ, et al., (2020). doi:10.1016/j.cmet.2019.11.004
  6. Moro T, et al., (2016). doi:10.1186/s12967-016-1044-0
  7. Lowe DA, et al., (2020). doi:10.1001/jamainternmed.2020.4153
  8. Gabel K, et al., (2018). doi:10.3233/NHA-170036
  9. Stote KS, et al., (2007). doi:10.1093/ajcn/85.4.981
  10. Cappuccio FP, et al., (2010). doi:10.1093/sleep/33.5.585
  11. Shi L, et al., (2018). doi:10.1016/j.smrv.2017.06.010