What Is Fasting? Everything You Need to Know

For centuries, people in various cultures and faiths around the world have abstained from food and/or drink in a ritual called “fasting.” This abstinence is performed for many reasons, from spiritual and religious purposes, to ethical protests, to medicine.

Fasting In Antiquity

Nearly every ancient culture throughout history has practiced fasting at one time or another, often as a form of purification (spiritual and/or physical).

Hunter/gatherer societies practiced fasting before going to hunt and in initiation ceremonies and many Aboriginal cultures fasted before going off to battle. Such men were later installed as chiefs, and considered very wise.

The ancient Hebrews, Egyptians, Syrians and Mongolians all fasted. Herodotus (484-425 B.C.E.) stated that the healthiest men during his time were the Egyptians, as they conduct a 3-day purification every month using enemas and vomiting. Their belief was that a person’s illness often comes through the food he eats.

Fasting was prominent in the ancient world of the Greeks, and is even found in mythology. Demeter, the mother of Persephone, was said to have fasted while in mourning for her daughter, and this ritual bled over into the Eleusinian Mysteries, an Athenian festival which honoured Demeter and Persephone, and required the participants to fast for one day.

Hippocrates, Pythagoras, Paracelsus, Socrates, Plato, Aristotle, and Galen, among other physicians and philosophers of old, all believed in the benefits of fasting.

Plutarch even advocated fasting instead of taking medicines. Pythagoras refused to teach his disciples until they had each undergone a 40-day fast!

Fasting In World Religions

Religious fasting is nearly (but not precisely) universal. From the Hellenistic mysteries to the shamans of Siberia (known as the Evenk), perhaps 95% of the world’s religions has practiced fasting at one time or another.

Some believed it would bring them closer to their god, either via visions or dreams; others felt it was the best method to appease the wrath of their deity, or to resurrect their god. Still others fasted as a form of penance.

Fasting as a strict, religious dietary law is found in Judaism, Islam and much of Christianity, due to its significant role in the Torah, Koran, and Bible.

The ancient Hebrews referred to the practice as innah nefes, which is the Hebrew phrase for “bodily affliction”.

From Exodus, Deuteronomy and Leviticus through to King David and later the prophet Daniel, the Torah abounds with references and descriptions of fasting. Moses was said to have fasted 40 days, twice. Fasting was used as a means of humbling oneself before God, or during times of mourning.

The ancient Hebrews also abstained from various foods on a permanent basis. Perhaps the most significant time of fasting, for them, was the Day of Atonement. This is still practiced by modern followers of Judaism, as are the original dietary practices as prescribed in the Torah.

For followers of Islam, fasting is non-negotiable. During the month of Ramadan, Muslims abstain not merely from food and drink, but smoking, and even intimate relations. Fasting is so strict in Islam that few exceptions (pregnancy, menstruation, illness, etc.) exist, and even these are subject to debate among the many schools of Islamic thought.

Vitamins are not permitted, and vomiting is considered breaking the fast. The Imami school even goes so far as to condemn swimming as a violation of the fast.

In Christianity, fasting is a sacred rite. While it is observed among the Catholics and Anglicans, it is perhaps the Eastern Orthodox Church which maintains the most complex rules and calendar.

What Is FastingOrthodox Christians fast over 200 days a year, with several of the fasts (Lent, Nativity) taking place for 40 days at a time, in reference to both Moses and Jesus. The Bible describes fasting in both the Old and the New Testaments, and Orthodox Christians are devoted to the practice.

During Lent, they abstain from meat, dairy and fish. Every Sunday from midnight on, the Orthodox devotee is expected to fast completely from everything including water (and in some parts of the world, this means refraining from brushing one’s teeth, too) before receiving Holy Communion at the Divine Liturgy.

Other Christians in the West vary on their beliefs regarding fasting. The Mormon Church (Church of Jesus Christ of Latter-Day Saints) practices Fast Sunday, wherein on the first Sunday of every month they abstain from eating two meals, and then donate the money it would have cost for those meals to the Church.

Pentecostals and other Charismatic Christians only fast if the Holy Spirit guides them, making it a personal choice as opposed to a rule.

For Methodists, fasting is an act of piety. Lutherans and other Protestants, on the other hand, do not subscribe to the practice.

Other religions for which fasting is extremely significant include Hinduism, Buddhism and Jainism. Taoism has even brought fasting into Chinese medicine. Sikhism, on the other hand, regards fasting as a waste of time, and Zoroastrianism forbids the practice altogether.

Fasting as a Form of Ethical Protest

Fasting is also used to protest war, the unethical treatment of citizens, and to express political or social perspectives. From 1913-1948, Mahatma Gandhi undertook not less than 17 fasts, the first being conducted as “atonement” for the violence committed by his followers (Gandhi taught nonviolence) in protest of Britain’s rule in India. Later, he fasted for other social demonstrations.

Since that time, many “hunger strikes” have been initiated for such purposes, some of the most famous being Dick Gregory’s 1960’s protest against the Vietnam War and the 1981 prison hunger strike in Belfast, which resulted in the deaths of 10 Irish nationalists. More recently, Chief Theresa Spence of the Attawapiskat First Nation conducted a 6-week hunger strike to protest the mishandling of Aboriginal issues and concerns in Canada.

Fasting for Medicinal Purposes

Fasting is required to achieve the correct results for many blood and urine tests, (i.e., Gestational Diabetes in pregnancy), etc. But what are the actual medicinal benefits of fasting?

In the 5th century B.C.E., Hippocrates began prescribing fasting as a means of healing patients suffering from specific illnesses. Hippocrates postulated that there is a doctor in each of us, and that we can heal ourselves. Food should be the medicine we can use to heal our bodies, but eating when we are sick means that we are also feeding our sickness.

The ancient Greeks prescribed fasting together with sleep, building hospitals called the “Temples of Sleep,” where their patients fasted and rested at all times until making a full recovery.

Fasting for Medical PurposeOver time, early physicians theorized about the “fasting instinct,” which was believed to be intimately connected with recovery. Physicians in late antiquity noted how some patients experienced loss of appetite during their affliction; they felt that patients in this state should not be fed until making a full recovery.

In the 19th century, studies began on the effects of fasting in humans and animals. By the 20th century, fasting evolved even as nutrition did, and many new and sophisticated approaches to fasting were developed, including as a method of disease prevention.

Some fasting treatment programs lasted as long as 30 days (or longer) and were conducted at home, in clinics or hospitals. These often included enemas and exercise, and patients were only permitted to drink water and certain teas lacking calories.

Later, doctors developed “modified fasting,” wherein adults were instructed to reduce their daily kilocalorie intake to 200-500, as opposed to the average medical recommendation of 1600-3000.  Juice, milk, honey, vegetable broth and bread were often the only food and drink consumed during these fasts.

Another type of fasting developed was intermittent fasting, wherein the patient fasts every second day.

Now, in the 21st century, fasting as a medical remedy is strongly debated. While some physicians argue that fasting is not particularly beneficial and may even be harmful in certain circumstances, others prescribe it together with a complete detoxification program, such as liver or lymphatic detox.

Medical studies on certain religious practitioners—Eastern Orthodox Christians and Muslims in particular—have demonstrated very encouraging results in regards to fasting, however.

Studies have shown that with an increased carbohydrate and decreased fat intake, various diseases of the respiratory, renal, neurological and other systems are often delayed or avoided altogether. The website for PMC (The US National Library of Medicine, National Institutes of Health) offers thorough resources and articles discussing this very subject at length.

In 2014, researchers at the University of Southern California published results of a remarkable study which showed that fasting aids in cell regeneration and boosts the immune system.

Fasting has also been shown to be useful in the treatment of diabetics. Dr. Jason Fung, a Canadian kidney specialist who founded the Intensive Dietary Management program and author of The Obesity Code, has stated that fasting is effective in curing Type 2 Diabetes (which is said to be irreversible).

According to Dr. Fung, he discovered the benefits of fasting on T2D while observing the effects of bariatric surgery on T2D patients. Bariatric surgery is a surgically-enforced, immediate “fast,” because of the way it instantly restricts excess calories.

Dr. Fung believes that insulin is the actual cause of obesity, and therefore, bariatric surgery and fasting in the treatment of T2D (as opposed to insulin injections) can not only heal diabetes, but cure obesity as well. Dr. Fung says that fasting from refined grains and white sugar, in addition to avoiding the constant snacking mentality of recent years, will decrease excess insulin levels, thereby reducing fats and gradually curing diabetes.

He explains that over the last several decades the standard three meals a day model has increased to six meals a day—breakfast, lunch and dinner, plus another three “snacks.” So our food intake has changed, therefore increasing our calorie intake and ultimately raising insulin and fat levels.

Dr. Fung cites not only his own research, but additional studies and statistics. One prime example is how starvation during the First and Second World Wars saw a massive drop in T2D mortality rates.

Interestingly, Dr. Fung also points out that the positive effects of fasting on diabetic patients was noted 100 years ago by Dr. Elliot Joslin, who discussed it in a 1916 article in the Canadian Medical Association Journal. It is therefore a curious fact that this correlation seems to have been lost until very recently.

Fasting Methods

In addition to the strict types of religious fasts and fasting for medical tests and/or treatments, here is a brief list of the more common types of fasting practiced today:

Dry Fasting:

Also called the Hebrew Fast, Black Fast or Absolute Fast, this is the most austere and severe of all fasting, and is practiced in many religions. It involves abstaining from all food and drink (including water) for varying lengths of time. Although it is rooted in deep mystical tradition, it is not medically recommended to attempt this type of fasting for any extended period.

Juice Fasting:

water-fastingThis method is popular and can, if done correctly, be beneficial. Not intended for use with juices from concentrate or ready-made, store-bought juices, juice fasting is accomplished by drinking “raw” fruit or vegetable juices made in a juicer. The nutritional benefits of this diet, as opposed to a water-only diet, are obvious, in that it offers a high vitamin count, and is essentially similar to maintaining a vegetarian diet.

Master Cleanse Lemonade Fasting:

This method became famous in the 1970s, and involves consuming lemonade mixed with maple syrup, salt water, an herbal laxative tea, and white and peppermint tea only, for the duration of the fast. Supporters of the Master Cleanse believe that it cleanses the intestinal tract.

Liquid Fasting:

This method of course involves only liquids. Acceptable liquids for this fast are: beer, broth, juice, lemonade, milk, and water.

Partial (Selective) Fasting:

Depending on which version of the fast is being subscribed too, this fast involves abstaining only from specific solid foods at certain times. An example is following a brown rice diet or mono-diet.