Andrea Kozlović, AOR COLUMNISTS

Fasting – a practice that helps the body, mind and spirit


When nothing means more

The principle of abstinence and its power on our lives is a long-known concept. As long as religions and philosophies have existed the concept of abstaining from certain things, thoughts or actions have been present, with the idea of living a better life and being a better person at its core.

In our ever so faster world, with instant gratification becoming the norm, informational overload, we are living in an unprecedented abundance. Maybe we don’t feel like we do, as we attach cultural meaning to certain words – abundance usually meaning surplus of money, but abundant is the world we live in. Our lives feel busy even if we never exit our home.

The idea of abstaining has been removed from our everyday lives as far as possible. We have the possibility to engage in all pleasurable things we want on daily basis, sometimes without ever moving. On the other side of the spectrum, we attach so much value to being busy and constantly working that we lose ourselves in the process of chasing ever so bigger goals.

This life rhythm is still very new to human species, while certain ancient practices still hold true and observing them can bring more value to our everyday life. We will explore the practice of fasting trough historical and religious lens, fasting health benefits, and discuss how mindfulness towards food and adopting the practice of periodical fasting can enrich our lives beyond just physical health.

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New generations - old ideas

The concept of periodic/intermittent and prolonged fasting has gained a lot of traction in the last ten years for its weight-loss and health promoting benefits. With current academic papers being published and positive personal experiences, it has become almost a daily occurrence in health portion of media outlets. 

The recent popularity of intermittent fasting today maybe has its roots in the fact that, in this day and age, we overconsume. We overconsume food, media, sex, anything that brings quick hit of pleasure. Intermittent fasting occurred as a direct antithesis of that. One somewhat forgotten practice stepped onto the mainstream, took the world by storm, and brought back to us ancient knowledge in a new, shiny packaged form.

For a while presented as a new fad diet, the knowledge of its benefits precedes today's research by millennia. 

People sharing some dried dates

Traditionally, fasting is not all about food

Principles of fasting have been ingrained in all major religions around the world. With the goal of developing higher consciousness, enlightenment and getting closer to God. Some earlier cultures like Inkas practiced fasting as a way to appease gods, while Babylonians fasted as a form of penance. From which ever aspect we observe the practice of abstaining from food, it has been a part of human culture from the earliest of times.

Most of religious fasting practices are observed under an umbrella of abstinence much broader than food – often encompassing abstinence from pleasurable and indulging things, shifting your attention towards meditation and prayer, and oftentimes giving to charity.

One of the most prominent traditions today is sawm – fasting, during the holy month of Ramadan in Islam, when they practice sawm between dawn and nightfall. As well as abstaining from food and water, ignorant and indecent speech, arguing and fighting, lustful thoughts and sexual relations are not permissible. The goal is to contemplate, pray, have kindness and compassion, and to be charitable within your own means. People who are sick, pregnant, nursing, menstruating or traveling are exempt from fasting, but they should make it up before next Ramadan. Children before puberty are also exempt from fasting.

In Buddhism fasting is observed as a practice of detachment rather than abstinence. In Buddhist philosophy it is important to balance body and mind – to avoid all causes of suffering and achieve the state of Nirvana. Buddhist monks eat 2 meals a day – one in the morning, and one before noon, while leaving the rest of the day for meditation, studying, helping the community and self-development. In certain Buddhist traditions monks rely on community to bring them food, thus detaching themselves from the desire of taste, and eating for vitality and balance. This also strengthens the connection between temples and the local community.

Focus is shifted towards practicing mindfulness while eating, understanding how cravings arise from pleasurable feelings and detaching oneself from desire which leads to suffering, on the other hand, fasting and abstaining from certain foods (vegetarianism in east Asian Buddhism) is seen as health and longevity promoting.  

Catholicism also observes a form of fasting and abstaining from food – weekly or biweekly on Wednesdays and Fridays – when they eat fish, and before Easter during the lent period, when they traditionally fast on Friday and Saturday, although, this differs trough different countries. The lent period is most commonly observed by abstaining from bad habits such as certain foods, behaviours, thoughts, it’s a period of introspection and prayer, where on a personal basis people choose what aspect on their life they wish to work upon.

In Hinduism fasting as a preparation for a Vedic ritual follows certain rules like good hygiene, celibacy, forbearance and abstaining from bad habits. In cases outside rituals, fasting must be done out one’s own free will, not out of fear and compulsion. Most Hindus break their fast by performing a traditional prayer ritual and by offering food to the gods. The food eaten to break a fast is dependent on the reason for the fast and the day of the week.

As well as in other religions and scriptures – moderation and simplicity are encouraged at all times, simple and healthy foods in appropriate amounts.

Ayurveda suggest fasting once a week to give our digestive system a break, but it does not recommend prolonged fast, since it can cause imbalances in the body and create health issues later on.

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We were not made for this

For early humans fasting was unavoidable. Hunther-gatherer humans depended on mercy and grace of nature, weather and seasons. During parts of the year food was scarce, and there were periods when the food was bountiful – so human metabolism adapted through millennia. We developed many biological mechanisms that helped us survive food scarcity. Those same mechanisms today aid in development of modern-day diseases – since, we were not made for eating 5 meals a day and enjoying a sedentary lifestyle for most of our lives.

Insulin as one example

The “selfish brain” theory hypothesizes that it may have played a central role in evolution of insulin resistance – 50% of body's glucose is consumed by 2% of its total mass – the brain. The brain is able to maintain a constant flux of large amounts of glucose while competing with fat and muscle tissue activating a stress system that includes the HPA axis and the sympathetic nervous system. This results in inhibition of insulin release in peripheral tissues and thus inducing insulin resistance and increasing hepatic glucose production. Leptin has also been hypothesized to be an evolutionary adaptation – it crosses the blood brain barrier informing the brain about the feeding and nutritional status of the rest of the body. High blood triglycerides that rise during starvation inhibit leptin transport which suggest that inhibition of leptin signalling could have survival advantages during starvation. [i]

As food availability changed trough millions of years our metabolism adapted. For the past 2 million years of our evolution, starting with Pleistocene glaciation, the diet was predominantly protein heavy and low carbohydrate, which has favoured insulin resistance, and resulted in increased hepatic gluconeogenesis and decreased peripheral glucose uptake.

Today we know that insulin resistance is a common denominator in many chronic diseases - hypertension, dyslipidaemia, diabetes type II., cardiovascular diseases, and an obesity epidemic. Insulin release is triggered mainly by carbohydrate consumption, to lesser extent by protein consumption, although generally (with certain exceptions such as consuming pure fat or calorie-less drinks) we can say that insulin is secreted with every snack, drink or meal.

Insulin increases lipogenesis in adipocytes (in layman's terms – more fat accumulation in your fat cells), decreases lipid catabolism, lowers thermogenesis and increases muscle mitochondrial oxidative capacity.  This evolutionary adaptation helped us survive by increasing our energy reserves during periods of carbohydrate rich food, and, with other mechanisms, helped us survive harsh winters and prolonged periods without food. Today, with us not moving enough and eating too much, it helps us become fatter and disease ridden.

As Rubio-Ruz et al. (2015) state: “If the combination of the human biological design and the current environment is no longer compatible and the species has developed a higher risk for diabetes and cardiovascular disease, prevention may be the most recommended action. Prevention measures should include modifying our current lifestyle to a style of life closer to that of our ancestors.”

There are way more evolutionary adaptations, beside insulin and leptin secretion, that influence our metabolism and we will leave those for some next post.

[i] María Esther Rubio-Ruiz, Ana Elena Peredo-Escárcega, Agustina Cano-Martínez, Verónica Guarner-Lans, "An Evolutionary Perspective of Nutrition and Inflammation as Mechanisms of Cardiovascular Disease", International Journal of Evolutionary Biology, vol. 2015, Article ID 179791, 10 pages, 2015.

Health benefits of periodical fasting

Periodical or intermittent fasting can have numerous health promoting benefits, as long as person incorporating fasting into their routine is healthy enough to do so, isn’t underweight, nursing or pregnant, or has eating disorders. Intermittent fasting can be done multiple of ways, depending on personal wants, needs and time management, but the most prominent approaches are 16/8 and OMAD (One Meal A Day). There are multiple changes that happen in the body in the period without food;

  • Insulin regulation improves[i][ii]
  • Human growth hormone levels increase[iii][iv]
  • Induces upregulation of autophagy markers and autophagy activation[v]
  • Promotes weight loss[vi]
  • Reduces oxidative stress and inflammation in the body[vii]
  • May improve brain health[viii]
  • May extend lifespan[ix][x]

IF modifies brain neurochemistry and neuronal network activity in ways that optimize brain function and peripheral energy metabolism. Four brain regions that are particularly important in adaptive responses to IF include the hippocampus (cognitive processing), striatum (control of body movements), hypothalamus (Hyp, control of food intake and body temperature), and brainstem (control of cardiovascular and digestive systems). The brain communicates with all of the peripheral organs involved in energy metabolism.

IF enhances parasympathetic activity (mediated by the neurotransmitter acetylcholine) in the autonomic neurons that innervate the gut, heart, and arteries, resulting in improved gut motility and reduced heart rate and blood pressure. By depleting glycogen from liver cells, fasting results in lipolysis and the generation of ketone bodies, causing a reduction in body fat.

IF enhances insulin sensitivity of muscle and liver cells and reduces IGF-1 production. Levels of oxidative stress and inflammation are reduced throughout the body and brain in response to IF.


The paradox of finding something in nothing

Fasting has been used as a spiritual tool for centuries. It is a tool at everyone’s disposal, one of the few things that cost nothing and brings multiple positive experiences and benefits if used correctly. Observed holistically and practiced with intention fasting heals the body, clears the mind and broadens own spiritual experience.

As I’ve spoken to people who utilize the practice of fasting outside from just health and physical benefits, multiple themes have been opened and pushed me into deeper pondering on how much more can we get out of this life if we set correct intentions, push ourselves a bit outside our comfort zone, and use the time we have to better ourselves or to get to know ourselves better.

People who fast religiously have talked about deepening their faith, gaining more clarity, having more compassion and a newly found appreciation for taste and food. The level of gratitude exponentially rises and leaves them happier and calmer. The switch in focus also happens, as they fast physically abstaining from food (and sometimes water), they also try to incorporate a food-unrelated fast or abstinence, sometimes from technology, behaviours they wish to change, while simultaneously incorporating practices that help them live the life they strive upon. They focus on the prayer, meditation, charity, school or learning. Everyone I’ve talked to describes their periods of spiritual fasting as enriching, learning experiences. Where they are able to work on things that no longer serve them, and parallelly gain much, much more.

I've also spoken to people who utilise the practice of fasting as a mean of getting out of creative ruts. People who periodically fast as a mean of problem solving. One person described it simply: “it is a walking meditation. In the very dynamic world filled with different energies – it helps me physically and spiritually. It brings me abundant mental clarity – any problem that arises it’s easily solvable”

The more research is done and published, the more we can see how two seemingly very opposing sides of religion and science begin to have a touching ground. While we set our intention to leave what no longer serves us, on the molecular level, autophagy, a process of recycling the old to make space for the new, takes place.

As I touched upon earlier, talking about our evolution, we evolved adapting to challenges, excluding certain stressors will make us more comfortable but we will deteriorate rapidly. Eustress is a term that explains that certain types of stressors promote positive changes in our bodies or for our mental health. We are made to be a bit uncomfortable, to reach a bit further and with that our bodies and our minds will respond positively.

It's a busy world we live in, we should allow ourselves to shift the focus from overconsumption, overstimulation, and information bombardment – to experience the empty, to bring some calm. Give our digestive system a break. Feel a bit lighter. Be still with oneself. Notice the thoughts that come up, the monkey brain, always everywhere, never still, never quiet. Bring focus to the breath, feel your heartbeat. This is the moment to be present. Allow the space to explore the sacredness of your own life.

[1] María Esther Rubio-Ruiz, Ana Elena Peredo-Escárcega, Agustina Cano-Martínez, Verónica Guarner-Lans, "An Evolutionary Perspective of Nutrition and Inflammation as Mechanisms of Cardiovascular Disease", International Journal of Evolutionary Biology, vol. 2015, Article ID 179791, 10 pages, 2015.

[1] Hoddy KK, Gibbons C, Kroeger CM, Trepanowski JF, Barnosky A, Bhutani S, Gabel K, Finlayson G, Varady KA. Changes in hunger and fullness in relation to gut peptides before and after 8 weeks of alternate day fasting. Clin Nutr. 2016 Dec;35(6):1380-1385. doi: 10.1016/j.clnu.2016.03.011. Epub 2016 Mar 30. PMID: 27062219.

[1] Adrienne R. Barnosky, Kristin K. Hoddy, Terry G. Unterman, Krista A. Varady,

Intermittent fasting vs daily calorie restriction for type 2 diabetes prevention: a review of human findings,

Translational Research, Volume 164, Issue 4, 2014, Pages 302-311, ISSN 1931-5244,

[1] Zhengxiang Huang, Lili Huang, Michael J. Waters, Chen Chen,

Insulin and Growth Hormone Balance: Implications for Obesity,

Trends in Endocrinology & Metabolism, Volume 31, Issue 9, 2020, Pages 642-654, ISSN 1043-2760,

[1] Horne BD, Muhlestein JB, Lappé DL, May HT, Carlquist JF, Galenko O, Brunisholz KD, Anderson JL. Randomized cross-over trial of short-term water-only fasting: metabolic and cardiovascular consequences. Nutr Metab Cardiovasc Dis. 2013 Nov;23(11):1050-7. doi: 10.1016/j.numecd.2012.09.007. Epub 2012 Dec 7. PMID: 23220077.

[1] Mohammad Bagherniya, Alexandra E. Butler, George E. Barreto, Amirhossein Sahebkar,

The effect of fasting or calorie restriction on autophagy induction: A review of the literature,

Ageing Research Reviews,

Volume 47,  2018, Pages 183-197, ISSN 1568-1637,

[1] Effects of 4- and 6-h Time-Restricted Feeding on Weight and Cardiometabolic Health: A Randomized Controlled Trial in Adults with Obesity, by: S.Cienfuegos, K.Gabel, F.Kalam et al. Volume 32, Issue 3, p366-378.E3, september 01, 2020, Published:July 15, 2020DOI:

[1] Aftab Ahmed, Farhan Saeed, Muhammad Umair Arshad, Muhammad Afzaal, Ali Imran, Shinawar Waseem Ali, Bushra Niaz, Awais Ahmad & Muhammad Imran (2018) Impact of intermittent fasting on human health: an extended review of metabolic cascades, International Journal of Food Properties, 21:1, 2700-2713, DOI: 10.1080/10942912.2018.1560312

[1] Mattson, M., Moehl, K., Ghena, N. et al. Intermittent metabolic switching, neuroplasticity and brain health. Nat Rev Neurosci 19, 81–94 (2018).

[1] Sarah J. Mitchell, Michel Bernier, Julie A. Mattison, Miguel A. Aon, Tamzin A. Kaiser, R. Michael Anson, Yuji Ikeno, Rozalyn M. Anderson, Donald K. Ingram, Rafael de Cabo,

Daily Fasting Improves Health and Survival in Male Mice Independent of Diet Composition and Calories,

Cell Metabolism, Volume 29, Issue 1, 2019, Pages 221-8.e3, ISSN 1550-4131,

[1] Xie, K., Neff, F., Markert, A. et al. Every-other-day feeding extends lifespan but fails to delay many symptoms of aging in mice. Nat Commun 8, 155 (2017).

[1] Valter D. Longo, Mark P. Mattson:Fasting: Molecular Mechanisms and Clinical Applications
Published:January 16, 2014, Cell Metabolism VOLUME 19, ISSUE 2, P181-192, FEBRUARY 04, 2014 DOI:

Andrea Kozlović

Andrea Kozlović

Certified nutritionist, with a love of ecology and biochemistry applied in a holistic approach to food and well-being.

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