time restricted eating window

Time Restricted Eating Window

I first heard about the notion of time restricted eating a few weeks back when it was discussed on Joe Rogan’s podcast The Joe Rogan Experience with guest Rhonda Patrick. I follow a ketogenic lifestyle that incorporates an intermittent fasting window of 16 hours fasting and 8 hours eating and tend to start my day very early with a nice, strongly brewed fresh bulletproof coffee, using butter and MCT oil. Previously, I thought that bulletproof coffee didn’t break my fast and was excluded from my eating window because it only contained healthy fats from the butter and MCT oil and these fats don’t trigger an insulin response. With this in mind, I thought my ‘eating window’ began  at lunchtime around 1pm.


I was so grateful that I listened to this podcast! Not only had I been doing it all wrong, I had also potentially discovered a way to break through my weight loss plateau and dramatically improve my metabolic rate, strength and endurance and have the potential to build lean muscle mass more effectively without having to increase the intensity of my workouts. Not to mention the opportunity to reduce the risk of breast cancer significantly. The answer? Time restricted eating!


How does using a time restricted eating window differ from intermittent fasting?


To break it down simply, the key difference between a time restricted eating window and intermittent fasting is that intermittent fasting uses an eating window that allows you to consume things outside of the window as long as they don’t break the fast by triggering an insulin response, such as healthy fats like coconut oil in a bulletproof coffee. When using a time restricted eating window, the clock begins ticking the very second you consume anything other than water, including a bulletproof coffee (or even a black coffee for that matter!).


What is it and how does it work?


The time restricted eating window, is the consumption of anything (other than water) within a certain time window that correlates to circadian rhythm. It has recently been proven to be an essential contributing factor towards metabolism, gut health and general health and wellbeing. With this in mind, I believe it could be used as a very effective tool to increase metabolic rate and aid weight loss, dramatically improve health by reducing disease risk factors and could even be used to reverse type 2 diabetes.


Consuming anything other than water requires processing by metabolic enzymes. These enzymes are effectively woken up when you ‘break your fast’, typically after sleeping, with your ‘breakfast’ of choice (be it a black coffee or full English)! The enzymes begin to process the food/drink by breaking it down, releasing energy from it, with their effectiveness being most potent at the start of this cycle, diminishing as time progresses. The maximum window for effectiveness is 12 hours. Anything beyond this time frame will not be effectively processed by the enzymes. Due to less insulin sensitivity during this time, one of the potential results of consumption beyond a 12 hour window is the addition of excess body fat.


As humans we are biologically engineered to be awake and active during predominantly daylight hours and sleep at night during nightfall. This is the reason that the enzymes are most effective during the daytime. Not only does their potency correlate to our circadian rhythm, they’re also triggered by daylight itself, the exact time when we should be expending the majority of our energy and therefore need it releasing from the food and drinks that we consume. The most effective time restricted eating window’s start as early in the day as possible and correlate with daylight.


Whilst sleeping, our energy requirements are very different. We are essentially comatosed and so require very little energy during this time in comparison to during the day when we are at our most active. This coincidentally is when the enzymes are least effective and active. After all, we fast whilst we sleep and so they’re not required to process our  in order to release energy just to kick the bed covers off a few time! The fact that there’s also typically the absence of daylight during this period also contributes to the fact that the enzymes are less productive during this time as daylight is a strong signalling factor for them.




The benefits of using a time restricted eating window are massive:

  • Help to reduce insulin resistance
  • Lower blood sugar levels
  • Assist with breaking through weight loss plateaus
  • Build lean muscle mass without the need for increase activity
  • Improve endurance
  • Improve mental clarity
  • Regulate hormones
  • Reduce inflammation
  • Alleviate the symptoms of anxiety and depression




The practicalities of adopting a time restricted eating window approach may be difficult for some, particularly around weekends, social events, family mealtimes and working hours, especially for those who do shift work. There are ways to work around this and adapt this way of living. You could fast in the morning and start your eating window later in the day. Although this approach may not correlate with circadian rhythm, eating within a time restricted window would definitely be more beneficial than not doing so. Preparation is also key. Take food with you if you know if you know you’ll be unable to prepare food during your window. If you have something to eat with you, there’s no excuse!




Dr. Satchin Panda is in the process of carrying out detailed studies on the efficacy of time restricted eating in humans. He has already carried out studies on mice, of which, the results are extremely profound. With research from the mice studies showing that whilst mice eating a healthy normal diet (not high fat and high sugar combined), may not gain weight, the same mice on the same diet, using a time restricted window (most effective was 9-10 hours) gained noticeably more muscle mass without increased levels of activity. In the same study, results show that if they ate within a 9 hour window their endurance improvement was remarkable!


The study showed the mice could ‘cheat’ 2 days out of 7 and extend their eating window with little to no effect on the benefits. Potentially great news if Dr. Satchin Panda’s research proves this theory in humans, because 5 days of compliance is far more doable for most of us, allowing 2 days to adapt the eating window around the weekend and social events.


Information is being gathered from around the world as I type this blog via an app. Check it out! It’s free to download and you can use it to track your eating window really easily. You can also opt to use your results as part of an ongoing study that, in my opinion, could revolutionise the way we all incorporate meal times into our daily lives. Be a part of history, sign up and help!


There’s also another useful app, designed by Kevin Rose to help keep track of your eating window during fasts. It gives you precise sunset times, which allows you to fast in sync with your circadian rhythm. This wonderfully effective tool is free forever too!


My experience using a time restricted eating window so far


Previously, I’d eat my main meal in the evening around 7pm, only a few hours before before bed (like most people do). After researching the time restricted eating window method, I learned that it isn’t the best idea to eat your biggest meal at the end of the day. That’s when your stomach enzymes are least effective and you don’t need all the energy from food because you’re asleep! Switching my main meal to lunchtime has had really positive affects on my digestive system by allowing my main meal to be processed by the enzymes whilst they are at their most effective. This in turn allows me to get the most energy from the food, which gives me a nice energy boost when it’s needed! I have also noticed that having a smaller meal in the afternoon, rather than a big meal a few hours before bed, has resulted in me getting a much better quality of sleep!


Having been on a weight plateau for a good few months now I was very happy to see a breakthrough implementing a 9 hour eating window. Hurrah! I have also noticed dramatic improvements in strength and endurance performance. So much so that i thought I’d mistakenly picked up a much lighter kettlebell before starting my workout last week. The difference was insane! I was flinging it around like it was a feather.




By viewing the time restricted eating window through an objective lens, it’s easy to see what a effective and powerful tool it truly is. After all, this way of consumption is biologically how we are designed to eat and drink and therefore our body is engineered to work optimally around this. It’s only as man has evolved and we have adopted dramatically different ways of consumption to it to suit our ever increasingly busy lifestyles that the demand for fast, instant, 24 hour consumption has evolved. The introduction of on demand, convenience food and drinks products have allowed us to dramatically extend the time frame during which we consume, extending our eating window way beyond one that our body is able to effectively work with. This, coupled with the fact that these products are predominantly junk (one for another blog!) in my opinion directly links to the state of public health and the dramatic shift downwards in the last 30 years!


My grandad always used to say that ‘it’s become too easy for people to eat’. By that, he meant the introduction of convenience food products and food outlets that enabled people to eat whatever, wherever. I believe that he raised a very worthy point. It was unheard of in his day to be ‘eating on the go’, because in his day meal times were routinely spent sat round a table with family or friends. He never understood why someone would want to walk down the high street in the early hours, munching on a fast food burger, sipping on a sugary drink. Mealtimes to him were an important part of his daily routine and I completely agree.


As human studies progress I’m excited by the prospect of learning more about this new way of consumption and i hope that the list of benefits continue to grow. With the potential to unlock the health of many millions by completely revolutionising the way in which we all look at eating and drinking, I believe the time restricted eating window may be the answer to many of our biggest health problems.

  • Pedro
    25th April 2017 at 4:18 pm

    I have always seen fasting as no food intake except water intake. As time has gone by humans have modified fasting to their needs or beliefs. Your time restricted eating is a true method of fasting.

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