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 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 be ...
. Many people may also fast as part of a medical procedure or a check-up, such as preceding a colonoscopy or surgery, or before certain medical tests. Intermittent fasting is a technique sometimes used for
weight loss
Weight loss, in the context of medicine, health, or physical fitness, refers to a reduction of the total body mass, by a mean loss of fluid, body fat (adipose tissue), or lean mass (namely bone mineral deposits, muscle, tendon, and other con ...
that incorporates regular fasting into a person's dietary schedule. Fasting may also be part of a religious ritual, 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 or ...
to mice with a bacterial or viral illness, or deprived them of carbohydrate. They found that carbohydrate was detrimental to bacterial
sepsis
Sepsis, formerly known as septicemia (septicaemia in British English) or blood poisoning, is a life-threatening condition that arises when the body's response to infection causes injury to its own tissues and organs. This initial stage is foll ...
. 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
biomarker
In biomedical contexts, a biomarker, or biological marker, is a measurable indicator of some biological state or condition. Biomarkers are often measured and evaluated using blood, urine, or soft tissues to examine normal biological processes, p ...
Fasting is always practised prior to surgery or other procedures that require general anesthesia because of the risk of
pulmonary aspiration
Pulmonary aspiration is the entry of material such as pharyngeal secretions, food or drink, or stomach contents from the oropharynx or gastrointestinal tract, into the larynx (voice box) and lower respiratory tract, the portions of the res ...
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 testing ( lipid panel) or certain blood glucose 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.
mood
Mood may refer to:
*Mood (psychology), a relatively long lasting emotional state
Music
*The Mood, a British pop band from 1981 to 1984
* Mood (band), hip hop artists
* ''Mood'' (Jacquees album), 2016
* ''Moods'' (Barbara Mandrell album), 1978
...
, 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
Weight loss, in the context of medicine, health, or physical fitness, refers to a reduction of the total body mass, by a mean loss of fluid, body fat (adipose tissue), or lean mass (namely bone mineral deposits, muscle, tendon, and other con ...
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
A protest (also called a demonstration, remonstration or remonstrance) is a public expression of objection, disapproval or dissent towards an idea or action, typically a political one.
Protests can be thought of as acts of coopera ...
, 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 language, Hindi ''rāj'': kingdom, realm, state, or empire) was the rule of the British The Crown, Crown on the Indian subcontinent;
*
* it is also called Crown rule in India,
*
*
*
*
or Direct rule in India,
* Q ...
and the Indian 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
Jesus, likely from he, יֵשׁוּעַ, translit=Yēšūaʿ, label=Hebrew/Aramaic ( AD 30 or 33), also referred to as Jesu ...
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 the ...
.
Muslims
Muslims ( ar, المسلمون, , ) are people who adhere to Islam, a monotheistic religion belonging to the Abrahamic tradition. They consider the Quran, the foundational religious text of Islam, to be the verbatim word of the God of Abra ...
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) 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 ( Mormons) 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
Asceticism (; from the el, ἄσκησις, áskesis, exercise', 'training) is a lifestyle characterized by abstinence from sensual pleasures, often for the purpose of pursuing spiritual goals. Ascetics may withdraw from the world for their p ...
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 po ...
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
''Mahāyāna'' (; "Great Vehicle") is a term for a broad group of Buddhist traditions, texts, philosophies, and practices. Mahāyāna Buddhism developed in India (c. 1st century BCE onwards) and is considered one of the three main existing bra ...
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
The Baháʼí Faith is a religion founded in the 19th century that teaches the essential worth of all religions and the unity of all people. Established by Baháʼu'lláh in the 19th century, it initially developed in Iran and parts of the ...
observe a Nineteen Day Fast from sunrise to sunset during March each year.
In alternative medicine
Although practitioners of
alternative medicine
Alternative medicine is any practice that aims to achieve the healing effects of medicine despite lacking biological plausibility, testability, repeatability, or evidence from clinical trials. Complementary medicine (CM), complementary and ...
natural hygiene
Orthopathy (from the Ancient Greek, Greek ὀρθός ''orthos'' 'right' and πάθος ''pathos'' 'suffering') or natural hygiene (NH) is a set of alternative medicine, alternative medical beliefs and practices originating from the ''Nature Cure ...
or new thought movement.Arnold 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. It also includes comments and notes to the articl ...
'', which made sensational claims of fasting curing practically all diseases, including
cancer
Cancer is a group of diseases involving abnormal cell growth with the potential to invade or spread to other parts of the body. These contrast with benign tumors, which do not spread. Possible signs and symptoms include a lump, abnormal bl ...
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, in w ...
.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
See also
*
Angus Barbieri's fast
Angus Barbieri (1939 – 7 September 1990) was a Scottish man who fasted for 382 days, from June 1965 to July 1966. He lived on tea, coffee, soda water, and vitamins while living at home in Tayport, Scotland, and frequently visiting Maryfield Ho ...
Anorexia nervosa
Anorexia nervosa, often referred to simply as anorexia, is an eating disorder characterized by underweight, low weight, Calorie restriction, food restriction, body image disturbance, fear of gaining weight, and an overpowering desire to be thi ...
*
Asceticism
Asceticism (; from the el, ἄσκησις, áskesis, exercise', 'training) is a lifestyle characterized by abstinence from sensual pleasures, often for the purpose of pursuing spiritual goals. Ascetics may withdraw from the world for their p ...
Weight loss
Weight loss, in the context of medicine, health, or physical fitness, refers to a reduction of the total body mass, by a mean loss of fluid, body fat (adipose tissue), or lean mass (namely bone mineral deposits, muscle, tendon, and other con ...
References
Further reading
*
Francis Gano Benedict
Francis Gano Benedict (October 3, 1870 – April 14, 1957) was an American chemist, physiologist, and nutritionist who developed a calorimeter and a spirometer used to determine oxygen consumption and measure metabolic rate.
Biography
Born ...
. (1915) ''A Study of Prolonged Fasting'' Carnegie Institution of Washington.
*
* Joan Jacobs Brumberg. (1988). ''Fasting Girls: The Emergence of Anorexia Nervosa As a Modern Disease''. Harvard University Press.
* Caroline Walker Bynum. (1987). ''Holy Feast and Holy Fast: The Religious Significance of Food to Medieval Women''. University of California Press.
* John Arthur Glaze. (1928). ''Psychological Effects of Fasting''. '' American Journal of Psychology'' 40 (2): 236–253.
* A. M. Johnstone. (2007) ''Fasting – the ultimate diet?'' '' Obesity Reviews'' 8 (3): 211–222.
* Walter Vandereycken, Ron Van Deth. (2001). ''From Fasting Saints to Anorexic Girls: The History of Self-Starvation''. Bloomsbury Academic.