Evidence Backed Benefits of Intermittent Fasting

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You will see that I am a big fan of intermittent fasting and have been for the last five years. I’ve experienced the benefits first hand, dropping forty pounds and getting into the best shape of my life. Originally it just suited my lifestyle and helped me cut calories, but over the years I’ve learned a lot about the multitude of benefits derived from intermittent fasting, and have spent many an hour researching in detail.

More and more research on intermittent fasting is being undertaken, and science is now backing a number of health, wellness and longevity benefits of fasting. My aim here is to cut through the many myths around fasting and to give you an objective view on the pros and cons of intermittent fasting. I’ve also aimed to keep the scientific and technical language to a minimum to demystify and simplify the benefits of intermittent fasting.

Based on personal experience and research into the science behind it, I am confident in asserting the benefits of intermittent fasting for a range of health and wellness benefits. It is a personal choice, but I hope this article gives you the information and tools to help you make a choice that suits your lifestyle, and health and wellbeing goals.


A Brief History of Fasting

Fasting broadly refers to the deliberate abstinence of food or drink for a set period of time. For the purposes of this article I will define fasting as the total abstinence from any and all calories for a defined period. Typically, this will mean abstinence from all food or drink except for water, green tea and black coffee. Intermittent fasting simply refers to an eating pattern that cycles between defined periods of fasting and non-fasting.

Fasting has a long history across multiple and varied traditions, often for health or spiritual reasons. The Greek philosopher Hippocrates, often regarded as the father of modern medicine, advocated fasting and believed that; “to eat when you are sick is to feed your illness”[1]. Plutarch and Plato were also big fans of fasting. The Greeks observed that sick animals did not eat and saw that it should be no different for humans. They believed fasting could both heal illness and improve cognitive function. As we will go on to discover they were correct! Fasting is still in practice in modern medicine (i.e. prior to surgery) and in recent times deeper studies are showing more benefits and potential applications for fasting within a medical context.

Likewise, almost all religious and spiritual practices throughout the ages have advocated fasting in one form or another. The Buddha, Jesus, and Prophet Muhammad[2] all fasted and believed in the power of fasting for physical, mental and spiritual benefit. A large number of religious fasting traditions are still practiced today[3]. Some of these traditions follow intermittent fasting patterns. For example, Ramadan involves abstaining from all food and drink from dawn to sunset for a whole month[4].

Intermittent Fasting in the Modern Era

In recent years intermittent fasting has also gained a lot of mainstream attention. It has been re-packaged multiple times in multiple guises, from the 16:8 protocol[5] to the 5:2 diet[6]. These are probably the best examples of the primary two methods of approaching things. 16:8 simply refers to sixteen hours of fasting, and eight hours of non-fasting each day. 5:2 refers eating normally for five days, and fasting for two days each week. So, in very simple terms you’re either cycling your fasts on a daily basis, or you’re dropping in full day fasts on an “intermittent” basis.

There are two threads I’d like to pull out from the previous paragraph. Firstly, weight loss is a potential benefit of intermittent fasting and it is an easy one to push to the mainstream. But, it also offers so many more potential benefits that we will go on to cover below. Secondly, how long does one need to fast for in order to call it a fast and see these health benefits listed below? Where possible I’ll try and cover that on a benefit by benefit basis, but the short answer is that you start seeing the health benefits of fasting after around twelve to sixteen hours, the point at which liver glycogen stores are depleted and fatty acids are mobilised[7].

To summarise, fasting just means not consuming any calories and intermittent fasting is cycling periods of fasting and non-fasting on a regular basis. I’m going to give you the science backed health and longevity benefits of fasting and a breakdown on the nutrition that will help you optimise these benefits. I’ll also touch on the potential mental and spiritual benefits and give you an insight into my own experiences of intermittent fasting.

Arguably health and longevity are intrinsically interlinked. Those that are healthy tend to live longer. So, I will now take a look at specifically what intermittent fasting can do for you, in terms of keeping you healthy and enabling you to live longer (and many of these benefits contribute to both sides of that coin).

Lower Risk of Disease

As noted above, sick animals tend to stop eating whilst they recover. And so it is with the human animal. Periods of fasting help you stay healthy. Studies have shown that intermittent fasting lowers cholesterol[8], lowers blood pressure[9], increases insulin sensitivity[10] and enables the body to metabolise fat and glucose far quicker than traditional diets[11], therefore reducing important risk factors for heart disease and diabetes[12].

Perhaps even more astounding, early studies in both animals and humans are also starting to show that fasting may have the potential to assist in slowing the onset or growth of cancer[13][14]. Beyond these specific cases of illness and disease, it has also been shown that fasting has the wide ranging benefit of boosting the immune system[15], protecting you from all manner of potential illnesses.

Maintain a Healthy Brain

The brain is pretty important. Although a relatively small proportion of your total mass, the brain accounts for around 20% of your body’s energy requirements. You might think that means it (and you) need constant refuelling. However, once again, fasting actually boosts the power of your brain! So, what have scientists uncovered?

Intermittent fasting protects your neurons (the specialised cells that transmit nerve impulses). Periods of fasting guard against excitotoxic stress[15] and accelerates autophagy (the process of clearing out damaged cells and generating new ones)[16]. In addition, it also increases the production of brain-derived neurotrophic factor (BDNF)[17]. These factors combined have multiple benefits including; improved memory[18], a reduction in cases of depression[19], and can potentially reduce or slow down cases Alzheimer’s[20][21].

Turbocharge Your Cells

You are your cells. They are the building blocks of life and your body is made up of trillions of cells. In simple terms cells keep us alive by regenerating. But it is this replication that also leads to our death. As cells replicate they can mutate, these mutations proliferate, in the end leading to degradation, illness and death. Furthermore, daily wear and tear causes oxidative stress (releasing free radicals[21]), and causing inflammation, both of which can accelerate cell degradation.

If we can keep our cells healthy it will help us to function at optimum levels, stay healthy, and live longer. Guess what? Fasting can help you with that. Intermittent fasting has been shown to increase the efficiency of cellular autophagy[22], and boosts stem cells regenerative capabilities[23]. On the flip side it decreases the degradation of mitochondria[24] (your cellular powerhouses), and reduces oxidative stress[25] and inflammation[26]. Remember, your whole body is made up of cells so this has wide ranging implications, and of course also overlaps with some of the aforementioned benefits.

Boost Biological Processes

Another key indicator of health and wellbeing is the efficiency of our biological processes. Is our body operating efficiently, are all chemicals and hormones in balance? If it is not then this puts undue stress on your body and can cause imbalances, and you guessed it, illness, cellular degradation and premature death! So, here is how fasting can help you get the body in sync.

Firstly, Intermittent fasting flips your metabolic switch and can dramatically improve metabolic efficiency as your glycogen supplies are depleted and your body switches to metabolising fatty acids[27], in turn improving circulating glucose and lipid levels[28]. Secondly, intermittent fasting has a positive impact on regulating important chemicals and hormones in your body[29]. This includes increases in human growth hormone[30], facilitating fat burning and muscle gain, and reduces insulin[31] which also facilitates fat burning.

Help with Weight Loss

I’ve left this one until last as it’s probably the most popularised benefit of fasting. As you’ll note from above some of the reasons for why intermittent fasting helps with weight loss. And it’s not just due to a caloric restriction. Intermittent fasting increases your metabolism, increases human growth hormone and reduces insulin levels, all of which lead to weight loss. Therefore, it can contribute to weight loss even without a major reduction in calories. However, intermittent fasting will typically contribute to a caloric restriction simply due to the shorter eating windows over time.

It is less clear whether or not intermittent fasting is more effective at helping people to maintain a healthy weight following weight loss. However, there are a number of studies emerging that are starting to address this question. Initial results suggest that intermittent fasting can indeed minimise weight gain, even for those that are consuming an “unhealthy” diet high in fat and sugar[32]. Of course, an unhealthy diet is likely to minimise or eliminate other health benefits of intermittent fasting.

Quality Nutrition Is the Key to Success

In light of that point, it is important to include a quick note on nutrition. Of course there are many ways to approach nutrition whether you are following intermittent fasting or not. However, the main point is that there are certain fixed principles that apply. Intermittent fasting is not a magical panacea for all your ills. If you fast, but you are eating a terrible diet of fast food with low nutritional value then clearly you are not going to reap the benefits.

Like anything in the health, wellness and longevity sphere, a good diet is just as important when it comes to fasting. It is important to eat a healthy diet full of nutrient dense foods, with the right balance of macro and micro nutrients. Also, as per usual it is important to minimise the intake of foods with low nutritional value such as processed foods etc. However, if you are already consuming a healthy diet then you can turbocharge the benefits through intermittent fasting.

Deeper Benefits for the Mind and Spirit

At the beginning of the article I referenced the long and varied history of religious and spiritual fasting practices. I feel it would be fitting to end the article with a nod to the mental and spiritual benefits of fasting. Some of these can be described by modern science (for example, improving memory or minimising depression). However, there are many other potential benefits that can only be referenced and understood through personal experience or through the collective body of experiences communicated by spiritual adepts throughout the ages.

Can fasting give you greater clarity, focus, energy or peace? Personally I have found that fasting gives me all of these things. As a person caught in the centre of a triangle made up of ancestral wisdom, spirituality and modern science it’s perhaps hard for me to be objective. However, as we evolve modern science and our understanding of the human body, mind and spirit I’m interested to see what we do uncover that can be quantified and explained. Or maybe these things are better left unknown, to be discovered and understood through individual experience. For those that fast, whether for health, religious or other reasons, I’d be interested to hear your thoughts on this topic.