Fasting is the abstention from eating and sometimes drinking. From a purely physiological context, "fasting" may refer to the metabolic status of a person who has not eaten overnight (see " Breakfast"), or to the metabolic state achieved after complete digestion and

absorption Absorption may refer to: Chemistry and biology *Absorption (biology), digestion **Absorption (small intestine) *Absorption (chemistry), diffusion of particles of gas or liquid into liquid or solid materials *Absorption (skin), a route by which s ...

of a meal. Metabolic changes in the fasting state begin after absorption of a meal (typically 3–5 hours after eating). A diagnostic fast refers to prolonged fasting from 1 to 100 hours (depending on age) conducted under observation to facilitate the investigation of a health complication, usually

hypoglycemia Hypoglycemia, also called low blood sugar, is a fall in blood sugar to levels below normal, typically below 70 mg/dL (3.9 mmol/L). Whipple's triad is used to properly identify hypoglycemic episodes. It is defined as blood glucose bel ...

. Many people may also fast as part of a medical procedure or a check-up, such as preceding a colonoscopy or

surgery Surgery ''cheirourgikē'' (composed of χείρ, "hand", and ἔργον, "work"), via la, chirurgiae, meaning "hand work". is a medical specialty that uses operative manual and instrumental techniques on a person to investigate or treat a pa ...

, or before certain medical tests. Intermittent fasting is a technique sometimes used for weight loss that incorporates regular fasting into a person's dietary schedule. Fasting may also be part of a

religious ritual A ritual is a sequence of activities involving gestures, words, actions, or objects, performed according to a set sequence. Rituals may be prescribed by the traditions of a community, including a religious community. Rituals are characterized ...

, often associated with specifically scheduled fast days, as determined by the religion.

Health effects

Fasting may have different results on health in different circumstances. To understand whether loss of appetite ( anorexia) during illness was protective or detrimental, researchers in the laboratory of Ruslan Medzhitov at Yale School of Medicine gave

carbohydrate In organic chemistry, a carbohydrate () is a biomolecule consisting of carbon (C), hydrogen (H) and oxygen (O) atoms, usually with a hydrogen–oxygen atom ratio of 2:1 (as in water) and thus with the empirical formula (where ''m'' may o ...

to mice with a bacterial or viral illness, or deprived them of carbohydrate. They found that carbohydrate was detrimental to bacterial sepsis. But with viral sepsis or influenza, nutritional supplementation with carbohydrates was beneficial, decreasing mortality, whereas denying glucose to the mice, or blocking its metabolism, was lethal. The researchers put forth hypotheses to explain the findings and called for more research on humans to determine whether our bodies react similarly, depending on whether an illness is bacterial or viral. Alternate-day fasting (alternating between a 24-hour "fast day" when the person eats less than 25% of usual energy needs, followed by a 24-hour non-fasting "feast day" period) has been shown to improve cardiovascular and metabolic biomarkers similarly to a calorie restriction diet in people who are overweight, obese or have metabolic syndrome. A 2021 review found that moderate alternate-day fasting for two to six months was associated with reductions of body weight, body mass index, and cardiometabolic risk factors in overweight or obese adults.

Medical application

Fasting is always practised prior to surgery or other procedures that require general anesthesia because of the risk of pulmonary aspiration of gastric contents after induction of anesthesia (i.e., vomiting and inhaling the vomit, causing life-threatening aspiration pneumonia). Additionally, certain medical tests, such as

cholesterol Cholesterol is any of a class of certain organic molecules called lipids. It is a sterol (or modified steroid), a type of lipid. Cholesterol is biosynthesized by all animal cells and is an essential structural component of animal cell memb ...

testing ( lipid panel) or certain

blood glucose Glycaemia, also known as blood sugar level, blood sugar concentration, or blood glucose level is the measure of glucose concentrated in the blood of humans or other animals. Approximately 4 grams of glucose, a simple sugar, is present in the b ...

measurements require fasting for several hours so that a baseline can be established. In the case of a lipid panel, failure to fast for a full 12 hours (including vitamins) will guarantee an elevated triglyceride measurement.

Mental health

In one review, fasting improved alertness, mood, and subjective feelings of well-being, possibly improving overall symptoms of depression, and boosting cognitive performance.

Weight loss

Intermittent fasting for periods shorter than 24 hours has been shown to be effective for weight loss in obese and healthy adults and to maintain lean body mass.

Complications

In rare occurrences, dry fasting can lead to the potentially fatal refeeding syndrome upon reinstatement of food intake due to electrolyte imbalance.

Historical medical studies

Fasting was historically studied on population under famine and hunger strikes, which led to the alternative name of "starvation diet", as a diet with 0 calories intake per day.

Other effects

It has been argued that fasting makes one more appreciative of food, and possibly drink.

Political application

Fasting is often used to make a political statement, to protest, or to bring awareness to a cause. A hunger strike is a method of non-violent resistance in which participants fast as an act of political protest, or to provoke feelings of guilt, or to achieve a goal such as a policy change. A ''spiritual fast'' incorporates personal spiritual beliefs with the desire to express personal principles, sometimes in the context of social injustice.Garcia, M. (2007) ''The Gospel of Cesar Chavez: My Faith in Action'' Sheed & Ward Publishing p. 103 The political leader Gandhi undertook several long fasts as political and social protests. Gandhi's fasts had a significant impact on the

British Raj The British Raj (; from Hindi ''rāj'': kingdom, realm, state, or empire) was the rule of the British Crown on the Indian subcontinent; * * it is also called Crown rule in India, * * * * or Direct rule in India, * Quote: "Mill, who was him ...

and the

Indian Indian or Indians may refer to: Peoples South Asia * Indian people, people of Indian nationality, or people who have an Indian ancestor ** Non-resident Indian, a citizen of India who has temporarily emigrated to another country * South Asia ...

population generally. In Northern Ireland in 1981, a prisoner, Bobby Sands, was part of the 1981 Irish hunger strike, protesting for better rights in prison. Sands had just been elected to the British Parliament and died after 66 days of not eating. 100,000 people attended his funeral, and the strike ended only after nine other men died. In all, ten men survived without food for 46 to 73 days. César Chávez undertook several spiritual fasts, including a 25-day fast in 1968 promoting the principle of nonviolence and a fast of 'thanksgiving and hope' to prepare for pre-arranged civil disobedience by farm workers.Shaw, R. (2008)''Beyond the Fields: Cesar Chavez, the UFW, and the struggle for justice in the 21st century'' University of California Press, p.92 Chávez regarded a spiritual fast as "a personal spiritual transformation". Other progressive campaigns have adopted the tactic.

Religious views

Fasting is practiced in various religions. Examples include Lent in

Christianity Christianity is an Abrahamic monotheistic religion based on the life and teachings of Jesus of Nazareth. It is the world's largest and most widespread religion with roughly 2.38 billion followers representing one-third of the global popula ...

; Yom Kippur,

Tisha B'av Tisha B'Av ( he, תִּשְׁעָה בְּאָב ''Tīšʿā Bəʾāv''; , ) is an annual fast day in Judaism, on which a number of disasters in Jewish history occurred, primarily the destruction of both Solomon's Temple by the Neo-Babylonian ...

, Fast of Esther, Tzom Gedalia, the

Seventeenth of Tamuz , observedby = Jews , date = 17th day of Tammuz , observances = Fasting, prayer , type = Jewish religious and national , significance = Date when the walls of Jerusalem were breached , relatedto = The fasts of the Tenth of Tevet and Tisha B'Av, ...

, and the Tenth of Tevet in

Judaism Judaism ( he, ''Yahăḏūṯ'') is an Abrahamic, monotheistic, and ethnic religion comprising the collective religious, cultural, and legal tradition and civilization of the Jewish people. It has its roots as an organized religion in th ...

. Muslims fast during the month of Ramadan each year. The fast includes refraining from consuming any food or liquid from sun up until sundown. Details of fasting practices differ. Eastern Orthodox Christians fast during specified fasting seasons of the year, which include not only the better-known Great Lent, but also fasts on every Wednesday and Friday (except on special holidays), together with extended fasting periods before Christmas (the Nativity Fast), after Easter (the

Apostles Fast The Apostles' Fast, also called the Fast of the Holy Apostles, the Fast of Peter and Paul, or sometimes St. Peter's Fast, is a fast observed by Eastern Orthodox, Oriental Orthodox, Eastern Catholic, and Reformed Orthodox Christians. In the Byzant ...

) and in early August (the

Dormition Fast The Dormition of the Mother of God is a Great Feast of the Eastern Orthodox, Oriental Orthodox, and Eastern Catholic Churches (except the East Syriac churches). It celebrates the "falling asleep" (death) of Mary the '' Theotokos'' ("Mother ...

). Members of the Church of Jesus Christ of Latter-day Saints (

Mormon Mormons are a religious and cultural group related to Mormonism, the principal branch of the Latter Day Saint movement started by Joseph Smith in upstate New York during the 1820s. After Smith's death in 1844, the movement split into se ...

s) generally abstain from food and drink for two consecutive meals in a 24-hour period on the first Sunday of each month.https://www.churchofjesuschrist.org/bc/content/ldsorg/topics/fasting-and-fast-offerings/PD60001350_TMP_2016%20LeadMtg_The%20Law%20of%20the%20Fast_9-15-16%20KW.pdf Like Muslims, they refrain from all drinking and eating unless they are children or are physically unable to fast. Fasting is also a feature of ascetic traditions in religions such as

Hinduism Hinduism () is an Indian religion or '' dharma'', a religious and universal order or way of life by which followers abide. As a religion, it is the world's third-largest, with over 1.2–1.35 billion followers, or 15–16% of the global p ...

and

Buddhism Buddhism ( , ), also known as Buddha Dharma and Dharmavinaya (), is an Indian religion or philosophical tradition based on teachings attributed to the Buddha. It originated in northern India as a -movement in the 5th century BCE, and ...

. Mahayana traditions that follow the Brahma's Net Sutra may recommend that the laity fast "during the six days of fasting each month and the three months of fasting each year". Members of the Baháʼí Faith observe a Nineteen Day Fast from sunrise to sunset during March each year.

In alternative medicine

Although practitioners of alternative medicine promote " cleansing the body" through fasting, the concept of "detoxification“ is marketing myth with few scientific basis for its rationale or efficacy. During the early 20th century, fasting was promoted by alternative health writers such as Hereward Carrington,

Edward H. Dewey Edward Hooker Dewey (21 May 1837 - 21 December 1904), best known as Edward H. Dewey, was an American physician. He was a pioneer of therapeutic fasting and the inventor of the "No Breakfast Plan". Career Dewey graduated from the College of Medic ...

, Bernarr Macfadden, Frank McCoy,

Edward Earle Purinton Edward Earle Purinton (April 24, 1878 – July 10, 1943) was an American businessman, naturopath, philosopher and self-help writer. Biography Purinton was born in Morgantown, West Virginia. He obtained his Bachelor of Arts from Denison Univer ...

, Upton Sinclair and

Wallace Wattles Wallace Delois Wattles (; 1860 – 7 February 1911) was an American New Thought writer. He remains personally somewhat obscure, but his writing has been widely quoted and remains in print in the New Thought and self-help movements. Wattles' bes ...

.Griffith, R. Marie. (2000). ''Apostles of Abstinence: Fasting and Masculinity during the Progressive Era''. '' American Quarterly'' 52 (4): 599-638. All of these writers were either involved in the natural hygiene or new thought movement.

Arnold Ehret Arnold Ehret (July 29, 1866 October 10, 1922)Melton, Gordon J. (1990). ''New Age Encyclopedia''. Gale Research. p. 159. was a German naturopath and alternative health educator, best known for developing the Mucusless Diet Healing System. Ehret ...

's pseudoscientific Mucusless Diet Healing System espoused fasting.Kuske, Terrence T. (1983)
''Quackery and Fad Diets''
. In Elaine B. Feldman. ''Nutrition in the Middle and Later Years''. John Wright & Sons. pp. 291-303. Linda Hazzard, a notable quack doctor, put her patients on such strict fasts that some of them died of starvation. She was responsible for the death of more than 40 patients under her care. In 1911, Upton Sinclair authored ''

The Fasting Cure ''The Fasting Cure'' is 1911 non-fiction book on fasting by Upton Sinclair. It is a reprinting of two articles written by Sinclair which were originally published in the ''Cosmopolitan (magazine), Cosmopolitan'' magazine. It also includes comment ...

'', which made sensational claims of fasting curing practically all diseases, including cancer, syphilis, and

tuberculosis Tuberculosis (TB) is an infectious disease usually caused by '' Mycobacterium tuberculosis'' (MTB) bacteria. Tuberculosis generally affects the lungs, but it can also affect other parts of the body. Most infections show no symptoms, ...

.Gratzer, Walter. (2005). ''Terrors of the Table: The Curious History of Nutrition''. Oxford University Press. p. 201. Sinclair has been described as "the most credulous of faddists" and his book is considered an example of quackery. In 1932, physician Morris Fishbein listed fasting as a fad diet and commented that "prolonged fasting is never necessary and invariably does harm".Fishbein, Morris. (1932)
''Fads and Quackery in Healing: An Analysis of the Foibles of the Healing Cults''
New York: Covici Friede. p. 253

References

External links

* * * * {{Authority control Asceticism Biologically-based therapies Diets Eating behaviors Fad diets Naturopathy Religious food and drink