What is it?
Early Time-Restricted Eating is a type of intermittent fasting that allows a limited time for eating each day. It is based around aligning our eating patterns with our circadian rhythms, the innate 24-hour cycles that tell our bodes when to wake up, when to eat and when to fall asleep, and is currently being championed by Dr. Satchin Panda a professor at the Salk Institute and an expert on circadian rhythms research.
What are the benefits?
lower levels of inflammation
better blood sugar control
lower risk for diabetes
better hormonal appetite control involving leptin and ghrelin
improved heart health
lower risk of cancer
improved brain function and lower risk of dementia
better stress management
more diverse gut flora
faster recovery after exercise
Does it make evolutionary sense?
Until very recently, eating 24/7 wasn’t even possible. For almost all of human history, people had to alternate between times of feasting and times of fasting. Many cultures have been practising intermittent fasting for religious reasons for millennia, and studying subjects who, for example, observed Ramadan – a way of time-restricted (but not calorie-restricted) eating showed that important health markers, such as blood pressure and cholesterol, improved after a month of intermittent fasting.
The approach stems from the idea that human metabolism follows a daily rhythm, with our hormones and digestive systems primed for food intake in the morning and afternoon. Many people, however, snack and graze from roughly the time they wake up until shortly before they go to bed. Research by Dr. Panda has shown that the average person eats over a 15-hour or longer period each day, starting with something like milk and coffee shortly after rising and ending with a glass of wine, a late night meal or a handful of chocolate, nuts or some other snack shortly after bed.
Scientists have long known that the human body has a master clock in the brain, located in the hypothalamus, that governs our sleep-wake cycles in response to bright light exposure. A couple of decades ago, researchers discovered that there is not just one clock in the body but a collection of them. Every organ has an internal clock that governs its daily activity.
During the day, the pancreas increases its production of insulin, which controls blood sugar levels, and then slows it down at night. The gut has a clock that regulates the daily ebb and flow of enzymes, the absorption of nutrients and the removal of waste. The communities of trillions of bacteria that comprise the microbiomes in our gut operate on a daily rhythm as well. These daily rhythms are so ingrained that they are programmes in our DNA.
Science now aligning with traditional medicine models?
With all the changes that have happened on this planet over thousands of years, one thing has remained constant: every single day the sun rises and at night it falls Dr. Panda says “We’re designed to have 24-hour rhythms in our physiology and metabolism. These rhythms exist because, just like our brains need to go to sleep each night to repair, reset and rejuvenate, every organ needs to have down time to repair and reset as well.
In Traditional Chinese Medicine is it said that each hour through the night is responsible for a different organ system regenerating itself, and if you have sleep disturbances at a regular time through the night, it could be your body’s way of telling you this organ system is in need of support. In Ayurveda, the sister science to yoga, it is believed that one should eat their largest meal of the day when the sun is at its strongest to support digestion, with a much lighter meal towards the end of the day. These century old beliefs are now being in confirmed in our evolving understanding of the circadian rhythm.
Can time-restricted eating help you lose weight?
Time-restricted eating means that for 12, 14 or 16 hours nothing will spike insulin and it is only in the absence of insulin that we can burn fat. Humans are designed to switch between using glucose (carbohydrate) and fat for fuel. We put down body fat as an energy reserve so that when food is scarce, we can live off that for a while. When we eat carbohydrates, insulin is secreted and one of the things it does is stop fat-burning. If we keep topping up insulin, we will have a harder time losing body fat. Even now, as we sleep, we are burning fat, as the body needs fuel through the night as well. Extending the overnight fast simply allows us to burn some more.
Should everyone restrict their eating window?
TRE may not work for everyone. If you are diabetic, very stressed or suffering from burnout or adrenal fatigue, it is important to get your blood sugar levels on to an even keel first and TRE is not recommended. Start with the Beginner version (see below for my guide on starting TRE) on just two non-consecutive days per week to see how you get on. If you have thyroid issues or a diagnosed medical condition or are on medication, speak to your nutrition practitioner before trying out TRE.
Everyone can start eating more in tune with their circadian rhythm and adapt an approach towards meals that supports that. A good rule of thumb is to follow the age-old saying: Eat breakfast like a king, lunch like a prince, and dinner like a pauper. This avoids going to bed with a full stomach when our body is trying to prepare us for sleep, and encourages you to have the majority of your food intake in the earlier part of the day when we burn calories and digest food more efficiently.
Interested in learning more?
During my online programmes I guide participants step by step in implementing Time Restricted Feeding Principles and ensuring they are personalising the approach to their health goals.
If you are keen to try it out for yourself here is a basic guide to get you started:
Beginners: 12:12 (12-eating window, followed by a strict fast for 12 hours)
Go Getters: 14:10
You can start bringing in TRF two days per week and slowly building up as you feel the benefits.