Time Restricted Eating: What you need to know

In one of my previous article (Let’s talk Science: High Carbohydrate Vs High Fat), I  talked about starting your day with a high fat meal (eg avocado and eggs, fat smoothie etc) vs the traditional approach of refined high carbohydrate breakfast (Eg. toasted muesli, cereal and toast). But why stop there! The benefits achieved  by this can be taken one step further by not eating at all and extending your overnight fasted period.

 

“Break” + “Fast” = Breakfast

Whether you like it or not you fast every night, while you are asleep. Therefore, the term “breakfast” is defined by breaking the overnight fast. Breakfast is known as one of the most important meals of the day. I will not debate this because I believe this to be true as it will set you up for your day. However the time when we consume it does not necessarily need to be first thing in the morning.

Isn’t skipping breakfast bad for you? What are the benefits of fasting? Is there any science behind this? Is it dangerous? These are all the questions that people will often ask as soon as you hear the word ‘fasting’

 

Do I fast?

Yes, in fact most days I fast from 14-18 hrs (7pm-11am ish). It is one of the most liberating things I have ever done and has allowed me to free up my mornings. My mornings are now more productive than ever before, I have a clear mind and do not waste time,  instead I can jump straight into the task at hand.

Why would I suggest people try fasting?

If you are interested health, longevity and sporting performance fasting is something that you should consider.

Let’s take a look at the research

Although intermittent fasting is a relatively new area of science fasting is ingrained to our history and is a component of almost every religion. It is only recently that we have been able to gain a deeper understanding of the physiological mechanisms at play and therefore identifying the positive benefits associated with intermittent / prolonged fasting/ time restricted eating as a powerful longevity enhancing strategy.

 

Animals Studies (9-12 hr eating window)

The majority has been performed in animal studies which have shown increased muscle mass, fat loss, glucose tolerance, improved lipid profiles, decreased inflammation, increase mitochondrial volume, protection against mild age fatty liver, protection against obesity, gene expression, increase production in ketone bodies. This list alone should be enough to highlight the amazing potential of fasting. But while this does appear in animal studies, will we see the same benefits in humans?

 

Humans Studies:

This is a growing body of literature and is still in its infancy in terms of research. Intermittent fasting/ time restricted eating (11 hr eating window) has been shown to decrease breast cancer risk (36%). It has also been shown to increase fat loss in overweight and obese people and interestingly for each 3 hr increase in time of the  overnight fast duration there was a 20% fall in HbA1c (long term marker of blood glucose levels and an indicator of normal, pre-diabetic and diabetic status).

Human Eating in 12 hr window:

Even with a more lenient fasting/ eating window of time, research has shown a number of significant benefits such as: improved sleep, weight loss, and decrease in inflammation.

 

HFLC vs Fasting

In previous post we have discussed the positive attributes associated with a high fat diet such as increased insulin sensitivity and reduction in inflammation. All of these benefits are seen with fasting and in most cases are substantially greater along with a few other added benefits that you are unable to achieve from a HFLC diet alone.

Fasting compared with HFLC, especially prolonged fasting,  presents a dramatic increase in autophagy and apoptosis followed by a massive increase in stem cell production. Autophagy is a genetic program which clears always damaged protein/s and organelles within the cell (think of it as cell ‘house cleaning’) while apoptosis is a process where damaged cells self destruct and break down, a controlled process that is part of any organisms growth or development.. Essentially the two process work to prevent the accumulation of senescent cells (old cells) within the body. The body is dynamic and is constantly turning over cells, manufacturing new ones or clearing damaged organelles within cells and in doing so this helps to maintain the health and functioning of the body (for the science nerd, it maintain homeostasis). The prevention of senescent cells accumulation can assist in reducing tumor growth. Increase in autophagy and apoptosis have been linked to longevity, with research in mice demonstrating that when these two processes are increased the life span can increase by ~20%.

Fasting also appears to impact the stem cell number and production. It is stem cells regenerative nature that helps in mitigating the effects of aging.

One of the biggest difference in comparing fasting to a HFLC diet is mitophagy.  Mitophagy is a process which clears damaged mitochondria (the cell power houses, where we generate our bodies energy source) and recycles their defective components which is followed by generation of new mitochondria through process of mitochondrial biogenesis. Once again this minimises the effects of ageing. HFLC has been shown to modestly increase mitochondrial biogenesis but not as much as mitophagy. Therefore to gain full benefit of mitophagy you would want to look at including fasted windows.

NAD (Nicotinamide adenine dinucleotide) increases in a fasted state and decreases in a feed state. NAD is an essential component for a wide range of enzymes to function properly. Your mitochondria need NAD for energy production from glucose or fatty acids and any time there is damage occurring in the body it sucks up NAD causing the mitochondria to suffer. Therefore the act of fasting offers the ability to up-regulate NAD in the absence of fuel.

Additionally, fasting promotes repair of DNA along with improved blood sugar regulation, insulin sensitivity, blood lipid profile and inflammatory markers (CRP, TNF alpha)

 

Application

There are varying opinions on what consists as a fast. Some are of the opinion, like Rhonda Patrick who follows the strictests of definitions. She states that consuming anything other water constitutes as ‘breaking the fast’. Others, define a fast as the window void of any calories and that you can have black coffee etc to help extend the fast.

Which definition you select to comply with will greatly depend on your life circumstances and the goals and benefits you are wanting to achieve.

With results being shown in human with even a 12 h fast window, it all comes down to designing a method that suits your lifestyle. The classic and most renowned intermittent fasting/time restricted eating method is the 16/8 (16 hour fast & 8 hour eating window). Grant Schofield, Caryn Zinn, & Craig Rodger from New Zealand recently released their new book following on from “What the Fat” This time focusing on fasting with “What the Fast”. I was lucky enough to be at their book release, this is a great resource packed full of evidence based practice for anyone looking for some guidance and with an alternative approach to intermittent fasting. In their approach they provide a great lifestyle approach to fasting which allows you to maximise your benefits without impacting and restricting

you. Their approach involves a monday tuesday full day fast with a very low carb/ fasting mimicking meal on monday and tuesday night. The rest of the week they encourage you to eat LCHF and on the weekends relax and prepare for the monday/tuesday fast. Their book is full of great recipes and if you are interested in fasting this is a great resource to get started!

When it comes to fasting I believe you need to view it as another tool and I don’t believe that you should be too strict on applying it. I find when most people begin especially your A-Type personalities they go all in and start pushing the limits far beyond what is needed and end up in a catabolic state. Instead my advice would be to listen to your body and when it wants fuel have fuel and as you train your body over time to become fat adapted and break free from your eating habits you will begin to thrive off your fasted windows. It is important to understand your fasted windows should not be tough! You should not be hungry, if you are then EAT! I am also not saying you should restrict your food intake during your eating window, this is not a starvation diet. During your eating windows, nourish your body with good wholesome food and enough to meet your energy and or training demands.

 

My approach:

I personally follow the less strict definition as most people tend to do and will have black coffee in a fasted state and often will even break this rule and add some MCT oil (Not true fast) to extend my fast or help assist with a fat adapting training session (I will discuss the in great detail in future posts)

 

Eating Window Consideration:

Circadian Impact (metabolism changes throughout the day)

Just like our bodies responds to light, our metabolism functions on a 24 hr cycle and changes throughout the day. Timing of food consumption can have altered effects on your body. For example, it has been shown that there is a greater postprandial (following meal) glucose response at dinner compared to breakfast. This is due to humans being dayianal creatures (function during the day). Therefore eating late at night will have a greater impact on our health. For each 10% increase in calories consumed after 5 pm was linked to a 3% increase in the inflammatory biomarker CRP.

 

Summary:

Reduction in systemic inflammation is thought to be one of the greatest predictors of health and longevity. Reduced inflammation is linked to improvements in age, prevention of cancer and mental health issues. Therefore a strategy like fasting or time restricted eating or anything that greatly impacts systemic inflammation is a positive and should be considered.

View fasting as a tool to add to the toolbox that can enhance your health and longevity, don’t get caught up and or get too strict.  Listen to your body and remember shifting to utilise fat for fuel takes time so don’t rush the change.

 

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