Published On: April 16, 2021866 words4.5 min read

Have you ever tried fasting at all? Fasting is not about starving. It is all about taking notice of good nutrition, and allowing the body to have time to digest good foods. It may well be another diet trend but one that is worth investigating.

This article is written by Thomas Sheehy, a yoga instructor and natural health coach with a special interest in diet, nutrition and lifestyle education. He offers personalised programmes for individuals and presents workshops on anatomy & physiology, nutrition, and digestive health. Thomas is currently undertaking MSc Adv. Complementary Medicine (Research & Practice).

If you are already a member of Tribe Sober, simply click on the “nutrition” Icon (in the members area) for more info about Thomas’ offer. If you are not a member yet, sign up HERE.

Intermittent fasting is a broad term for a variety of ways to manipulate the timing of food intake in order to improve body composition and overall health. Intermittent fasting is commonly grouped into ‘alternate-day’ fasting and ‘time-restricted’ feeding. Each form of intermittent fasting utilizes different periods of feeding and fasting.[1]

Alternative-day fasting may consist of 24hr fasts followed by a 24hr eating period, and can be done several times a week, such as a 5:2 strategy when there are two fast days mixed into five non-fast days. Time-restricted fasting may include 16hr fasts with 8hr feeding times; for example, eating only between the hours of 10am-6pm; or other similar versions such as 20hr fasts with 4hr feeding windows.[2]

Although intermittent fasting has gained popularity in recent years, humans have actually fasted throughout history. Our hunter-gatherer ancestors didn’t have supermarkets, refrigerators or food available year-round; meaning we couldn’t always find anything to eat and our bodies have evolved to be able to function without food for periods of time.

Intermittent fasting can induce a ‘ketogenic state’ which signals a switch from fat storage to fat utilization, resulting in decreased low-density lipoproteins (LDL) and increased high-density lipoproteins (HDL) levels. This change from using glucose as energy to using fatty acids and ketones for energy is called ‘intermittent metabolic switching’ and promotes weight loss because processing ketones requires greater energy.[2]

 Similarities and differences between intermittent fasting and caloric restriction[1]

 By relieving the body of the work of digesting foods, fasting allows the system to rid itself of toxins; enabling healing and repair of damaged tissues. During a period of fasting the following things occur;[3]

  • The process of toxin excretion continues, while the influx of new toxins is reduced.
  • The immune system’s workload is reduced, allowing it to concentrate on existing inflammation and allergies etc.
  • Fat stored chemicals such as pesticides and drugs are released from body tissues.
  • Physical awareness and sensitivity to diet and surroundings is increased.
  • A fast can help to cleanse the liver, kidneys and colon; purifying the blood, aiding weight loss, diminishing water retention and improving the appearance of the eyes, hair and skin.

A word of warning

Despite the benefits of fasting, it must be undertaken with care. A body that is overloaded with environmental pollutants can produce unpredictable reactions as the cocktail of chemicals hits the bloodstream. Common side effects of fasting include headaches, nausea, dizziness, skin rashes, increased body odour, aching limbs and muscles, insomnia and more.

Fasting is contra-indicated during pregnancy and breast feeding, in infancy, for people with kidney and liver disease and anyone who regularly takes prescription drugs.[4] People with medical conditions should consult their medical practitioner prior to undertaking a period of fasting.

However, for those who can weather the initial storm the rewards are great; increased energy, concentration and even intuition, as well as decreased pain and inflammation are commonly reported.

“To fast is to abstain from food while one possesses adequate reserves to nourish vital tissues.

To starve is to abstain from food after reserves have been exhausted so that vital tissues are sacrificed.”

– Joel Fuhrman

Certain precautions should be taken during fasting. Fasting on water alone can release toxins too quickly leading to ‘detox crisis’ symptoms such as headaches, nausea and worse. Additionally, although a typical diet provides too much salt, fasting usually provides too little. If you feel lightheaded or dizzy you might include some broth in the diet.

There is no single diet that meets the needs of every person; individual needs vary depending on factors such as physical activity, plus mental and emotional wellbeing; and are also influenced by age, gender, body size and physique, exercise and workload, physiological and biochemical characteristics, personal tastes and preferences etc. It is recommended to consult with a nutrition expert before undertaking any form of fasting, in order to tailor a fasting programme to suit your individual needs.



1: Tinsley, G.M. and La Bounty, P.M., 2015. Effects of intermittent fasting on body composition and clinical health markers in humans. Nutrition Reviews, 73(10), pp.661–674.

2: Dong, T., Sandresara, P., Dhindsa, D., Mehta, A., Arneson, L., Dollar, A., Taub, P. and Sperling, L., 2020. Intermittent Fasting: A Heart Healthy Dietary Pattern? Physiology & Behavior, 176(3), pp.139–148.

3: Balch, P., 2010. Prescription for Nutritional Healing. 5th ed. New York: Avery.

4: Murray, M. and Pizzorno, J., 2012. The Encyclopedia of Natural Medicine. 3rd ed. New York: Atria.




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