Fasting and Intermittent Fasting has become a very popular dietary tool in the last few years. Many people have started incorporating some form of fasting to help with weight loss, diabetes, digestive issues, inflammation and longevity. There are a lot of physicians and people in the wellness sphere who recommend intermittent fasting for many ailments. Proponents of fasting describe health benefits such as increased energy levels, more focus and decreased appetite. Whilst those may seem like fantastic improvements, you may not realise that these may not be promoting our long term health.
Fasting was a concept I was familiar with from my teenage years when I read a book about yoga and fasting and was intrigued. It’s also practised in various religions so is not a modern concept. A while back, I started exploring the idea of fasting in relation to digestive health and longevity, and started to implement it into my daily routine. I would generally skip breakfast, and have an 8 hour eating window. Sometimes, when I was busy, my eating window would be even narrower, and the more I fasted the less hungry I became, which I believed was a sign of health (!!). After a while, however, my health began to deteriorate: I started losing my hair, my mood became unstable, I started to get joint pain, my regular periods started to go a bit wonky and I experienced PMS symptoms for the first time in years, and I started putting ON weight, especially around my middle. I had my thyroid tested and it was the worst it has ever been. This is a pattern I have noticed with some of my clients as well as some of my college students: fasting working great to start with…until it doesn’t.
In this blog post I am going to explain why I no longer recommend fasting to my clients and why I choose am approach of nourishment versus deprivation – let me know if you have experienced any of these symptoms by introducing this practise in your lifestyle. And if these resonate with you and you would like to switch to an abundance approach, then we should definitely talk!
Our body needs nutrients to function optimally
All of our body systems need nutrients to function: without nutrients, the body will prioritise the systems essential for survival (heart, brain, respiration) and downregulate the non-essential functions: digestion, reproduction, healthy hair, nails and skin.
Our body’s sole purpose is to keep us alive, and when we go longer period without food, our blood sugar will drop and our pancreas will secrete glucagon, whose purpose is to mobilise all our glycogen stores in the liver and muscle tissue to make glucose to get keep our blood glucose levels in the optimal range. This is because our brain, our tissues and pretty much every cell in our body runs on glucose. Our body will also start breaking down proteins to make glucose (this is a process called gluconeogenesis). This includes our own muscle tissue, ligaments and other glands such as our thymus gland – which is important for immune function.
Our body will also start to break down fats to use for fuel – a part of these will go to generate more glucose and some will be sent into the bloodstream as free fatty acids to be used as energy by organs such as the heart. You may be thinking ‘but isn’t using fat for fuel a good thing, especially if that means it’s breaking down my own fat stores?’ You’d think so, but actually a lot of the fatty acids in our bodies are polyunsaturated (from eating processed foods, vegetable oils, taking fish oil supplements etc) and polyunsaturated fats have been shown to have a thyroid suppressing action, so in the long run, using these fatty acids for fuel can impact our thyroid function and slow down our own metabolism.
(If you really fancy nerding out on the physiological changes which occur with fasting, this is a great video.
Fasting is a stress on the body.
Now let’s get this straight – the process mentioned above is a stress state for the body. Our bodies have these backup mechanisms in place in order to keep us alive in times of famine, but that does not mean that this should be our preferred process to run on. Not having enough food and consequent low blood sugar will trigger the release of cortisol, our ‘anti- stress’ hormone, whose sole purpose is to get us through the stress period. It will facilitate the breakdown of our own muscles, connective tissue and glands for glucose, and to help us survive it will also downregulate digestion and reproduction. This is a survival mechanism, and thank goodness it exists, but do we want to simply survive or do we want to thrive?
We have seen in previous blog posts how stress can affect our hormonal health too – when the body senses a stressor, it will produce cortisol. Cortisol is synthesised from progesterone (our true female hormone, in my opinion) and without enough progesterone we are more likely to experience estrogen dominance, which can manifest as irregular periods, migraines, premenstrual symptoms, painful menstruation, mood fluctuations, thyroid dysfunction and more sinisterly issues such as fibroids, endometriosis, PCOS and fibrocystic breasts.
I often get asked by students or clients about the benefits of fasting and one of the explanations I like to give is this: if you were to go to a retreat in the Swiss Alps and do a period of fasting there, where you spend most of your days laying around on a lounger in the sun, gazing at your beautiful surroundings, reading books, resting and having daily massages, then fasting may be a stress your body can handle at that time and may have health promoting properties. But most of us are not fasting in a luxurious 5 star health spa, are we? We are fasting whilst running around like headless chickens, juggling work and life, emotional and environmental stressors, not sleeping optimally or enough, perhaps forcing ourselves to exercise on top of that…fasting is just another added layer of stress which we do not need and which will ultimately deplete our body’s resilience and metabolism.
Intermittent fasting often leads to undereating during our eating window
One of the trends I have noticed with fasting is that most people will not eat enough during their ‘eating window’, and this could be one of the main mechanisms for weight loss with intermittent fasting. It is not surprising that if we cut our calories or skip a complete meal, we will lose weight to start with. But if this caloric restriction is imposed for longer periods of time, eventually our body will start adapting to the lowered energy input and simply adjust our metabolism to run on this amount of calories. This can lead to a more sluggish metabolism, dysregulated thyroid function and people putting on weight as soon as the fasting is stopped and normal eating patterns are resumed.
Furthermore, studies have shown that intermittent fasting for 12 weeks actually increases fat reserves and reduces muscle reserves in animals, so whilst there may be an initial weight loss with fasting, the long term benefits may be a lot less desirable. And studies on overweight and obese patients showed that time restricted eating did not confer any weight loss or cardiometabolic benefits versus eating throughout the day.
Fasting can affect our vitamin D levels.
Studies have shown that fasting will decimate vitamin D levels and may actually contribute to diabetes. Vitamin D has a role in energy production and there is a lot of evidence to show that low vitamin D levels can be a driver for metabolic diseases. One study showed that fasting reduced a liver enzyme for vitamin D synthesis by 50% after 12 hours of fasting, signalling a suppression of Vitamin D signaling during nutrient deprivation. By 24 hours, no vitamin D was detected. Vitamin D is known to protect the liver from cortisol induced injury as well as inhibiting estrogen receptors, so without adequate levels of this hormone through fasting
So why do people feel better when they start fasting?
The main reason is cortisol secretion. The focus and mental clarity we get during the fasting period is mainly due to the release of this hormone. The main functions of cortisol during the alarm phase are to heighten our senses so we are able to assess our immediate situation and make a split second decision, or to help us go out and hunt to sustain ourselves.
Cortisol also triggers the release of sugar into our bloodstream to give us the energy to run away from an angry bear…which may explain why we feel so energised during our fasting window (or after an intense workout).
The lack of hunger we experience is again due to cortisol secretion – if we are in a life or death situation, the last thing we need is a rumbly tummy to distract us, right? A well known sign of stress is lack of appetite. Think about it: why would our bodies ever want to suppress hunger, the driving force that sets us out to seek nourishment and keeps us alive? Lack of appetite is not a symptom we should strive for, and actually waking up in the morning with an appetite is a sign of a well-functioning metabolism.
Some people may experience temporary relief in symptoms such as inflammation. Again, this is all thanks to cortisol, which decreases our sensitivity to pain as a coping mechanism when we are in fight or flight mode. One thing to keep in mind as well that a symptomatic relief does not always mean long term resolution.
One final point to keep in mind too is that just because something feels good, it does not necessarily mean it’s health promoting. Alcohol and drugs can make the user feel good temporarily, but their health will deteriorate in the long run. A lot of us are used to running on stress hormones and might actually feel worse when we tap into our true metabolic state – this may not feel great to begin with, but it is a starting point upon which we can begin to rebuild our health. More on this in a future blog post!
But what about our ancestors who experienced periods of feast and famine?
This is an argument I hear a lot and one which used to make sense to me as well. However, I have come to realise that the periods of famine our ancestors endured were not done so by choice – I highly doubt that our ancestors would actively pass up the opportunity to eat if given the option. Sure, our body has a backup system to keep us alive during times of famine, but as I explained earlier, this is not its preferred system to run on. We need nutrients to thrive! This is a fantastic article which goes into the ancestral argument about fasting, if you would like to explore this further, but in essence concludes that “Intermittent fasting, and dieting in general, is a modern phenomenon that is the result of some kind of search for meaning in a society that seems spiritually dead but materially sated,”
On top of that, our modern life is full of stressors which our ancestors were not exposed to: constantly being on the go, work/ life stressors, overexercising, pollution, chemicals in our environment and in our home/ personal products, light pollution, blue light exposure 24 hours a day etc. Our body needs nutrients to deal with stress, and by depriving it of food we are adding
So, in summary, the reasons for me to no longer recommend fasting are multiple. After experiencing its long term effects myself, and seeing similar patterns in both clients and college students, I have come to realise that an approach of nourishment versus deprivation is a lot more conducive to long term health. Rather than depriving our body of nutrients and calories, how about flooding it with all the substances it needs to truly thrive, so that it can not only keep our survival systems working, but also our digestion, hormonal, reproduction and other systems such as our nails, skin and hair to flourish!
I can see the benefits of fasting as a therapeutic protocol in certain states of disease, but for general health and well being – especially for hormonal health, fertility and weight management – I prefer to focus on an approach of abundance! So I would like to ask you – are you ready to try a different approach to health this year? One of nourishment and abundance versus one of deprivation? If you are ready to feel empowered and back in control of your health, click here to book a free discovery call and let’s chat about how some bespoke diet and lifestyle changes can help you flourish.
Is Intermittent Fasting ‘Natural’? History experts respond to the controversy. https://www.inverse.com/article/57835-intermittent-fasting-evolution
Ultrastructure of the thymus in diabetes mellitus and starvation https://link.springer.com/article/10.1007/s12325-008-0010-5
Intermittent Fasting for Twelve Weeks Leads to Increases in Fat Mass and Hyperinsulinemia in Young Female Wistar Rats https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7230500/
Effects of Time-Restricted Eating on Weight Loss and Other Metabolic Parameters in Women and Men With Overweight and Obesity https://jamanetwork.com/journals/jamainternalmedicine/article-abstract/2771095?guestAccessKey=444bbcb2-7e13-4dc6-998f-5de5e27aa19e&utm_source=For_The_Media&utm_medium=referral&utm_campaign=ftm_links&utm_content=tfl&utm_term=092820
Fasting-Induced Transcription Factors Repress Vitamin D Bioactivation, a Mechanism for Vitamin D Deficiency in Diabetes https://diabetes.diabetesjournals.org/content/68/5/918