Fasting refers to the act of willingly abstaining from the consumption of food and/or fluids, for a period of time. A fast may be total or partial, and may vary in duration and frequency. Depending on the tradition involved, fasting practices may preclude sexual activity as well as food, or specify certain types of foods to be avoided, such as refraining from eating meat.
Fasting for religious and spiritual reasons has been a part of human custom since pre-history. The practice is mentioned in the Bible, in both the Old and New Testament, the Qur'an, the Mahabharata, and the Upanishads. Fasting is particularly important for Muslims during the holy month of Ramadan and for Christians during Lent. Since fasting involves exercising control of the physical body, many religions consider fasting a way to cultivate mental discipline, and use it in connection with prayer or meditation to make it a more powerful experience.
- 1 Religious fasting
- 1.1 Bahá'í faith
- 1.2 Buddhism
- 1.3 Christianity
- 1.4 Hinduism
- 1.5 Islam
- 1.6 Jainism
- 1.7 Judaism
- 1.8 Sikhism
- 2 Medical fasting
- 3 Physiological effects of fasting
- 4 Notes
- 5 References
- 6 External links
- 7 Credits
In modern medicine, fasting is the state achieved after digestion of a meal. A number of metabolic adjustments occur during fasting and many medical diagnostic tests are standardized for fasting conditions. For most medical purposes, a person is assumed to be fasting after 8-12 hours. A diagnostic fast refers to prolonged fasting (from 8-72 hours depending on age) conducted under medical observation for investigation of a problem, usually hypoglycemia. Fasting has occasionally been recommended as a therapeutic intervention by physicians of many cultures, though it is currently quite uncommonly resorted to for this purpose by modern doctors, albeit medical fasting can be a way to promote detoxification.
Fasting is an important practice in many of the world's religions, carried out for a variety of reasons. A religious person may fast to cultivate personal discipline and spiritual energy, as a form of self-mortification, to commemorate special events, to follow tradition, or to symbolize and enact detachment from the world.
Fasting is one of the greatest obligations of a Bahá'í. In the Bahá'í Faith, fasting is observed from sunrise to sunset during the Bahá'í month of `Ala' (between March 2 through March 20). It involves the complete abstention from both food and drink (as well as smoking). Observing the fast is an individual obligation, and is binding on all Bahá'ís who have reached the age of maturity, which is 15 years of age.
Fasting is generally considered by Buddhists as a form of asceticism and as such is rejected as a deviation from the Middle way. Nevertheless, Theravada Buddhist monks and nuns, who follow the Vinaya monastic rules, traditionally do not eat each day after the noon meal. However, this is not considered a fast, but rather a disciplined regime aiding in meditation.
The Vajrayana practice of Nyung Ne is based on the tantric practice of Chenrezig. It is said that Chenrezig appeared to Gelongma Palmo, an Indian nun who had contracted leprosy and was on the verge of death. Chenrezig taught her the method of Nyung Ne in which one keeps the eight precepts on the first day, then refrains from both food and water on the second. Although seemingly against the Middle Way, this practice is to experience the negative karma of both oneself and all other sentient beings and, as such, is seen to be of benefit.
Fasting is a practice in several Christian denominations and churches. Other Christian denominations do not practice it, seeing it as a merely external observance, but many individual believers choose to observe fasts at various times at their own behest, and the Lenten fast observed in Anglicanism is a 40-day partial fast to commemorate the fast observed by Christ during his temptation in the desert. The Book of Isaiah, chapter 58:3-7, discusses fasting saying it means to abstain from satisfying hunger or thirst, and any other lustful needs we may yearn for. The blessings gained from this are claimed to be substantial. The opening chapter of the Book of Daniel, verses 8-16, describes a partial fast and its effects on the health of its observers.
Biblical accounts of fasting
- Moses fasted for 40 days and 40 nights while he was on the mountain with God. (Exodus 34:28)
- King David fasted when the son of his adulterous union with Bathsheba was struck sick by God, in punishment for the adultery and for David's murder of Bathsheba's husband, Uriah the Hittite. Nevertheless, the son died, upon which David broke his fast (2 Samuel 12:15-25).
- King Jehosaphat proclaimed a fast throughout Judah for victory over the Moabites and Ammonites who were attacking them (2 Chronicles 20:3).
- The prophet Isaiah chastised the Israelites in Isaiah 58 for the unrighteous methods and motives of their fasting. He clarified some of the best reasons for fasting and listed both physical and spiritual benefits that would result.
- The prophet Joel called for a fast to avert the judgement of God.
- The people of Nineveh in response to Jonah's prophecy, fasted to avert the judgement of God (Jonah 3:7).
- The Jews of Persia, following Mordechai's example, fasted due to the genocidal decree of Haman. Esther declared a three-day fast for all the Jews prior to risking her life in visiting King Ahasuerus uninvited (Book of Esther 4).
- The Pharisees in Jesus' time fasted regularly, and asked Jesus why his disciples did not. Jesus answered them using a parable (Luke 5:33-39, Matthew 9:14-15, Mark 2:18-20).
- Jesus also warned against fasting to gain favor from men. He warned his followers that they should fast in private, not letting others know they were fasting (Matthew 6:16–Matthew 6:18).
- Jesus fasted for forty days and forty nights while in the desert, prior to the three temptations (Matthew 4:2, Luke 4:2).
- Jesus said : But this kind does not go out except by prayer and fasting. (Matthew 17:21)
- And he (Jesus) said unto them (disciples), This kind can come forth by nothing, but by prayer and fasting. (Mark 9:29)
- The prophetess Anna, who proclaimed the birth of Jesus in the Temple, fasted regularly (Luke 2:37).
- There are indications in the New Testament as well as from the Apocryphal Didache that members of the early Christian Church fasted regularly.
Denominations and groups
For Charismatic Christians fasting is undertaken at the leading of God. Fasting is done in order to seek a closer intimacy with God, as well as an act of petition. Some take up a regular fast of one or two days a week as a spiritual observance. Holiness movements, such as those started by John Wesley, Charles Wesley, and George Whitefield in the early days of Methodism, often practice such regular fasts as part of their regimen.
Eastern Orthodox Church
Wednesdays and Fridays are also fast days throughout the year (with the exception of fast-free periods). In some Orthodox monasteries, Mondays are also observed as fast days (Mondays are dedicated to the holy Angels, and monasticism is called the "angelic life").
Fasting during these times also includes abstention from animal products (meat and often fish), olive oil (or all oils, according to some Orthodox traditions), and wine (which is interpreted as including all alcoholic beverages).
Fasting can take up a significant portion of the calendar year. The idea is not to suffer, but to use the experience to come closer to God, to realize one's excesses, and to engage in almsgiving. Fasting without increased prayer and almsgiving (donating to a local charity, or directly to the poor, depending on circumstances) is considered useless or even spiritually harmful by many Orthodox Christians.
Those desiring to receive Holy Communion keep a total fast from all food and drink from midnight the night before.
Certain festal periods are fast-free, meaning that fasting is forbidden, even on Wednesdays and Fridays (though fasting before Holy Communion is never relaxed, except for health reasons). These periods are:
- The 12 days from the Nativity of Christ to Theophany (Epiphany)
- The week following Pascha (Easter)—and during the 50 days from Easter Sunday to Pentecost, the fasting laws are lessened, wine and oil being permitted even on Wednesdays and Fridays
- The week following Pentecost
Oriental Orthodox Churches
With exception of the 50 days following Easter in the Coptic Orthodox Church fish is not allowed during Lent, Wednesdays, Fridays, and Baramon days. Other than that fish and shellfish are allowed during Fasting days.
The discipline of fasting entails that apart from Saturdays, Sundays and Holy feasts should keep a total fast from all food and drink from midnight the night before to a certain time in the day usually three o'clock in the afternoon (The hour Jesus died on the Cross), Also it is preferred to practice the reduction of one's daily intake of food (typically, by eating only one full meal a day).
In Protestantism, the continental Reformers criticized fasting as a purely external observance that can never gain a person salvation. The Swiss Reformation of the "Third Reformer" Huldrych Zwingli began with an ostentatious public sausage-eating during Lent.
On the other hand, churches of the Anglican Communion and some American Protestant denominations, such as the United Methodist Church, affected by liturgical renewal movements encourage fasting as part of both Lent and Advent, two penitential seasons of the Liturgical Year.
Likewise, Lutheran churches encourage fasting during lent. They also encourage it before partaking in the Eucharist, as Martin Luther writes in his Small Catechism: Who, then, receives such Sacrament worthily? Fasting and bodily preparation is, indeed, a fine outward training; but he is truly worthy and well prepared who has faith in these words: Given, and shed for you, for the remission of sins.
Other Protestants consider fasting, usually accompanied by prayer, to be an important part of their personal spiritual experience, apart from any liturgical tradition.
For Roman Catholics, fasting is the reduction of one's intake of food to one full meal (which may not contain meat during Fridays in Lent, only fish) and two small meals (known liturgically as collations, taken in the morning and the evening). Eating solid food between meals is not permitted. Fasting is required of the faithful on specified days. Complete abstinence is the avoidance of meat for the entire day. Partial abstinence prescribes that meat be taken only once during the course of the day. To some Roman Catholics, fasting still means consuming nothing but water.
Pope Pius XII had initially relaxed some of the regulations concerning fasting in 1956. In 1966, Pope Paul VI in his apostolic constitution Paenitemini, changed the strictly regulated Catholic fasting requirements. He recommended that fasting be appropriate to the local economic situation, and that all Catholics voluntarily fast and abstain. In the United States, there are only two obligatory days of fast - Ash Wednesday and Good Friday. The Fridays of Lent are days of abstinence: those observing the practice may not eat meat. Pastoral teachings since 1966 have urged voluntary fasting during Lent and voluntary abstinence on the other Fridays of the year. The regulations concerning such activities do not apply when the ability to work or the health of a person would be negatively affected.
Prior to the changes made by Pius XII and Paul VI, fasting and abstinence were more strictly regulated. The church had prescribed that Catholics observed fasting and/or abstinence on a number of days throughout the year.
In addition to the fasts mentioned above, Catholics must also observe the Eucharistic Fast, which involves taking nothing but water and medicines into the body for some time before receiving the Eucharist during the Mass. The ancient practice was to fast from midnight until Mass that day, but as Masses after noon and in the evening became common, this was soon modified to fasting for three hours. Current law under Vatican II requires merely one hour of eucharistic fast, although some Catholics still abide by the older rules.
The Rule of Saint Benedict and a vast body of ascetic writings, speak in great detail about fasting.
The Church of Jesus Christ of Latter-day Saints
Latter-day Saint fasting is total abstinence from food and water. Adherents are encouraged to fast totally for two consecutive meal times once a month, and the first Sunday of the month is usually designated a Fast Sunday. Some Latter-day Saints also avoid partaking of the previous Saturday evening meal; others abstain from breakfast and lunch on Fast Sunday. Importance is placed on the attitude of one fasting, rather than on a legalistic debate over how long the fast should continue. The money saved by not having to purchase and prepare meals is donated to the church as a fast offering, which is used to help people in need. LDS President Gordon B. Hinckley asked: “What would happen if the principles of fast day and the fast offering were observed throughout the world[?] The hungry would be fed, the naked clothed, the homeless sheltered. … A new measure of concern and unselfishness would grow in the hearts of people everywhere.” (“The State of the Church,” Ensign May 1991, 52–53.)
Sunday worship meetings on Fast Sunday include opportunities for church members to publicly express thanks and to bear their testimony of faith.
Since fasting involves exercising control of the physical body, subjugating it to the mind, many Latter-day Saints consider fasting a way to focus on the spiritual body, and use it in connection with prayer to make it more meaningful.
Fasting is a very integral part of the Hindu religion. Individuals observe different kinds of fasts based on personal beliefs and local customs. Some examples are listed below:
- Some Hindus fast on certain days of the month such as Ekadasi or Purnima.
- Certain days of the week are also set aside for fasting depending on personal belief and favorite deity.
- Thursday fasting is very common among the Hindus of northern India.
- Fasting during religious festivals is also very common. Common examples are Maha Shivaratri or the nine days of Navratri (which occurs twice a year in the months of April and October/November during Vijayadashami just before Diwali, as per the Hindu calendar). Karwa Chauth is a form of fasting unique to the northern part of India where married women undertake a fast for the well-being, prosperity, and longevity of their husbands. The fast is broken after the wife views the moon through a sieve after sunset.
Methods of fasting also vary widely and cover a broad spectrum. If followed strictly, the person fasting does not partake any food or water from the previous day's sunset until 48 minutes after the following day's sunrise. Fasting can also mean limiting oneself to one meal during the day and/or abstaining from eating certain food types and/or eating only certain food types. In any case, even if the fasting Hindu is non-vegetarian, he/she is not supposed to eat or even touch any animal products (i.e., meat, eggs) on a day of fasting.
In Islam, fasting is an obligatory practice during the holy month of Ramadan, from fajr (dawn), until maghrib (sunset). Muslims are prohibited from eating, drinking, smoking, and engaging in sexual intercourse while fasting. Fasting in the month of Ramadan is one of the Pillars of Islam, and thus one of the most important acts of Islamic worship. By fasting, a Muslim draws closer to Allah by abandoning the things they enjoy, such as food and drink. This makes the sincerity of their faith and their devotion to Allah all the more evident.
The Qur'an states that fasting was prescribed for those before them (i.e., the Jews and Christians) and that by fasting a Muslim gains taqwa, which can be described as the care taken by a person to do everything God has commanded and to keep away from everything that He has forbidden. Fasting helps prevent many sins and is a shield with which the Muslim protects him/herself from jahannam (hell).
Muslims believe that fasting is more than abstaining from food and drink. It also includes abstaining from any falsehood in speech and action, from any ignorant and indecent speech, and from arguing and fighting, and lustful thoughts. Therefore, fasting helps develop good behavior.
Fasting also inculcates a sense of fraternity and solidarity, as Muslims feel and experience what their needy and hungry brothers and sisters feel. However, even the poor, needy, and hungry participate in the fast. Moreover, Ramadan is a month of giving charity and sharing meals to break the fast together.
While fasting in the month of Ramadan is considered wajib (obligatory), Islam also prescribed certain days for non-obligatory, voluntary fasting, such as:
- each Monday and Thursday of a week
- the 13th, 14th, and 15th day of each lunar month
- six days in the month of Shawwal (the month following Ramadan)
- the Day of Arafat (9th of Dhu al-Hijjah in the Hijri (Islamic calendar))
- the Day of Ashuraa (10th of Muharram in the Hijri calendar), with one more day of fasting before or after it.
There are many types of fasting in Jainism. One is called Chauvihar Upwas, in which no food or water may be consumed until sunrise the next day. Another is called Tivihar Upwas, in which no food may be consumed, but boiled water is allowed. Fasting is usually done during Paryushana but can be done during other times. If one fasts for the eight days of Paryushana, it is called Atthai. It is also common for Jains to limit their intake of food. When a person only eats lentils and tasteless food with salt and pepper as the only spices, the person is said to do Ayambil. This is supposed to decrease desire and passion. Self-starvation by fasting is known as Sallekhana and is supposed to help shed karma according to Jain philosophy.
Another form of fasting is Santhara, the Jain religious ritual of voluntary death by fasting. Supporters of the practice believe that Santhara cannot be considered suicide, but rather something one does with full knowledge and intent, while suicide is viewed as emotional and hasty. Due to the prolonged nature of Santhara, the individual is given ample time to reflect on his or her life. The vow of Santhara is taken when one feels that one's life has served its purpose. The goal of Santhara is to purify the body and, with this, the individual strives to abandon desire.
Fasting for Jews means completely abstaining from food and drink, including water. For Orthodox Jews, Taking medication, or even brushing teeth is forbidden on the major fast days of Yom Kippur and Tisha B'Av, but permitted on minor fast days. Observant Jews fast on six days of the year. With the exception of Yom Kippur, fasting is never permitted on Shabbat, for the commandment of keeping Shabbat is biblically ordained and overrides the later rabbinically-instituted fast days. Yom Kippur is the only fast day which is explicitly stated in the Torah.
Yom Kippur is considered to be the most important day of the Jewish year and fasting as a means of repentance is mandatory for every Jewish man and boy above the age of bar mitzvah and every Jewish woman and girl above the age of bat mitzvah. It is so vital to fast on this day, that only those who would be put in danger by fasting are exempt, such as the ill, elderly, or pregnant or nursing women. Those that do eat on this day are encouraged to eat as little as possible at a time and to avoid a full meal. For some, fasting on Yom Kippur is considered more important than the prayers of this holy day. If one fasts, even if one is at home in bed, one is considered as having participated in the full religious service. In addition to fasting and prayer, Yom Kippur—as the "Sabbath of the Sabbaths" has the same restrictions regarding "work" as the Sabbath. Carrying outside of the home, using electricity, cooking, riding in a car, using the telephone, writing, etc. are all forbidden. No leather shoes are worn on this day. Men may wear a white gown (kittel) over their clothes, symbolic of a burial shroud on this Day of Judgement. Some women may often wear a large white scarf over their heads and do not put on make-up or jewelry. The aura of the day is serious, humble, sacred and repentant yet happy in the knowledge that sincere repentance brings redemption.
The second major day of fasting is Tisha B'Av, the day nearly 2000 years ago on which the Romans destroyed the Holy Temple in Jerusalem and the Jews were banished from their homeland. Tisha B'Av ends a period of nine days in which Jews do not participate in happy events, wash clothes, eat meat except on the Sabbath, cut hair or swim. In general, these nine days and to some extent the entire three weeks before Tisha B'Av are considered a time of danger for Jews. Historically, this timeframe has been ripe with persecutions and other tragic events. Unlike the fast of Yom Kippur, there are no restrictions on activities, although one should try to avoid doing regular work the first part of the day, sit in a low chair or on the floor, and wear no leather shoes. This is also the day when observant Jews remember the many tragedies which have befallen the Jewish people, including the Holocaust. The atmosphere of this holiday is serious and deeply sad.
Both of these holy days are considered major fasts and are observed from sunset to sunset the following day by both men and women. The remaining four fasts are considered minor and fasting is only observed from sunrise to sunset. Men must observe them, and women should observe them, but a rabbi may often give dispensations if the fast represents too much of a hardship to a sick or weak person.
The minor fast days are:
- The Fast of Gedaliah
- The Fast of the 10th of Tevet
- The Fast of the 17th of Tammuz,
- The Fast of Esther, which takes place immediately before Purim
Additional fast days such as the Fast of the Firstborn, which only applies to first-born sons; family-instituted fasts in remembrance of a miraculous delivery from tragedy, which only apply to certain families or to certain regions; communal fasts in the face of impending calamity in order to arouse benevolence from the Heavens; or personal fasts as a means of repentance are not undertaken by the entire Jewish community.
On the two major fast days it is also forbidden to engage in any sexual relations, wash or bathe, apply cosmetics or creams, and even wear leather shoes, which are considered a symbol of extravagance. Partial or total exemptions apply in many cases for those who are ill, those for whom fasting would pose a medical risk, pregnant women, and nursing mothers. Those who would be endangered from fasting are forbidden to do so, as endangering one's life is against a core principle of Judaism.
Aside from these official days of fasting, Jews may take upon themselves personal or communal fasts, often to seek repentance in the face of tragedy or some impending calamity. For example, a fast is observed if the scrolls of the Torah are dropped. The length of the fast varies, and some Jews will reduce the length of the fast through tzedakah, or charitable acts.
It is customary for a bride and groom to fast on their wedding day before the ceremony as the day represents a personal Yom Kippur. Repentance prayers that are only said on Yom Kippur are included by the bride and groom in the service before the ceremony
Purpose of fasting in Judaism
Judaism views three essential potential purposes of fasting, and a combination of some or all of these could apply to any given fast. One purpose in fasting is the achievement of atonement for sins and omissions in Divine service. Fasting is not considered the primary means of acquiring atonement; rather, sincere regret for and rectification of wrongdoing is key (see Isaiah, 58:1-13, which appropriately is read as the haftorah on Yom Kippur).
Nevertheless, fasting is conducive to atonement, for it tends to precipitate contrition in the one who fasts (see Joel, 2:12-18). This is why the Bible requires fasting (lit. self affliction) on Yom Kippur (see Leviticus, 23:27,29,32; Numbers, 29:7; Tractate Yoma, 8:1; ibid. (Babylonian Talmud), 81a). Because, according to the Hebrew Bible, hardship and calamitous circumstances can occur as a result of wrongdoing (see, for example, Leviticus, 26:14-41), fasting is often undertaken by the community or by individuals to achieve atonement and avert catastrophe (see, for example, Esther, 4:3,16; Jonah, 3:7). Most of the Talmud's Tractate Ta'anit ("Fast[s]") is dedicated to the protocol involved in declaring and observing fast days.
The second purpose in fasting is commemorative mourning. Indeed, most communal fast days that are set permanently in the Jewish calendar fulfill this purpose. These fasts include: Tisha B'Av, Seventeenth of Tammuz, Tenth of Tevet (all of the three dedicated to mourning the loss of the destroyed Temple in Jerusalem), and Fast of Gedaliah. The purpose of a fast of mourning is the demonstration that those fasting are impacted by and distraught over earlier loss. This serves to heighten appreciation of that which was lost. This is in line with Isaiah (66:10), who indicates that mourning over a loss leads to increased happiness upon return of the loss:
- Be glad with Jerusalem, and exult in her, all those who love her; rejoice with her in celebration, all those [who were] mourners over her.
The third purpose in fasting is commemorative gratitude. Since food and drink are corporeal needs, abstinence from them serves to provide a unique opportunity for focus on the spiritual. Indeed, the Midrash explains that fasting can potentially elevate one to the exalted level of the Mal'achay HaSharait (ministering angels) (Pirkei d'Rabbi Eliezer, 46). This dedication is considered appropriate gratitude to God for providing salvation. Additionally, by refraining from such basic physical indulgence, one can more greatly appreciate the dependence of humanity on God, leading to appreciation of God's beneficience in sustaining His creations. Indeed, Jewish philosophy considers this appreciation one of the fundamental reasons for which God endowed mankind with such basic physical needs as food and drink. This is seen from the text of the blessing customarily recited after consuming snacks or drinks:
"You are the Source of all blessing, O' Eternal One, our God, King of the universe, Creator of many souls, who gave [those souls] needs for all that which You created, to give life through them to every living soul. Blessed is the Eternal Life-giver."
Sikhism is probably the only major organized world religion that does not promote fasting except for medical reasons. The Sikh Gurus discouraged the devotee from engaging in fasting as it allegedly "brings no spiritual benefit to the person." The Sikh holy scripture, Sri Guru Granth Sahib tell us: "Fasting, daily rituals, and austere self-discipline - those who keep the practice of these, are rewarded with less than a shell."(SGGS, 216). therefore, in general, Sikhs do not undertake fasting.
People can also fast for medical reasons, such as preparing for surgery or other procedures that require anesthetic. Since the presence of food in a person's system can cause complications during anesthesia, medical personnel strongly suggest that their patients fast for several hours (or overnight) before the procedure.
Another reason for medical fasting is to prepare for certain medical tests, such as cholesterol testing (lipid panel). People are often asked to fast so that a baseline can be established. In the case of cholesterol, the failure to fast for a full 12 hours (including vitamins) will guarantee an elevated Triglyceride measurement.
A longer fast for health reasons typically lasts a week or longer and includes some food intake, such as fruit or vegetable juices, as part of a detox diet.
Some doctors believe that pure water fasting can not only detoxify cells and rejuvenate organs, but can actually cure  such diseases and conditions as cardiovascular disease, rheumatoid arthritis, asthma, high blood pressure, type 2 diabetes, colitis, psoriasis, lupus and some other autoimmune disorders when combined with a healthy diet. They believe that "Fasting is Nature's Restorer."
Recent studies on mice show that fasting every other day while eating double the normal amount of food on non-fasting days led to improved insulin and blood sugar control, neuronal resistance to injury, and health indicators superior to mice on 40 percent calorie restricted diets. Alternate day calorie restriction may prolong lifespan and attenuates diseases associated with inflammation, oxidative stress and aging.
People who feel they are near the end of their life sometimes consciously refuse food or water. The term in the medical literature is patient refusal of nutrition and hydration. Contrary to popular impressions, studies indicate that "within the context of adequate palliative care, the refusal of food and fluids does not contribute to suffering among the terminally ill," and might actually contribute to a comfortable passage from life: "At least for some persons, starvation does correlate with reported euphoria."
In natural medicine, fasting is seen as a way of cleansing the body of toxins, dead or diseased tissues, and giving the gastro-intestinal system a rest. Such fasts are either water-only, or consist of fruit and vegetable juices. Fasting has also been used in the treatment of some kinds of cancer, autoimmune diseases,and allergies.
Common terms used in research are: reduced diet therapy (RDT), Fasting Therapy (FT) and caloric restriction. Research tends to originate from Russia, Japan, and Germany.
Physiological effects of fasting
When food is not eaten, the body looks for other ways to find energy, such as drawing on glucose from the liver's stored glycogen and fatty acids from stored fat and eventually moving on to vital protein tissues. Body, brain and nerve tissue depend on glucose for metabolism. Once the glucose is significantly used up, the body's metabolism changes, producing ketone bodies (acetoacetate, hydroxybutyrate, and acetone). Even where this transition to alternative forms of energy has been made, some parts of the brain still require glucose, and protein is still needed to produce it. If body protein loss continues, death will ensue.
- Isaiah 58:3-13 Bible Gateway. Retrieved July 10, 2020.
- There are some exceptions to this rule: Children under the age of ten; Serious illness; If one is traveling; Women who are pregnant and too physically weak; A woman during her menstrual period.
- Joel Fuhrman, Fasting and Eating for Health: A Medical Doctor's Program for Conquering Disease (St. Martin's Griffin, 1995, ISBN 031218719X), 1, 3, 21-23, 56-59, 70-72, 79-81.
- Fuhrman, 13.
- R. Michael Anson, Rafael de Cabo, Titilola Iyun, Michelle Rios, Adrienne Hagepanos, Donald K. Ingram, Mark A. LaneDagger, Mark P. Mattson, Intermittent fasting dissociates beneficial effects of dietary restriction on glucose metabolism and neuronal resistance to injury from calorie intake Proceedings of the National Academy of Sciences of the United States of America 100 (10): 6216-6220 The National Academy of Sciences of the United States of America, May 13, 2003. Retrieved July 10, 2020.
- Ruiqian Wan, Simonetta Camandola, Mark P. Mattson, Intermittent Food Deprivation Improves Cardiovascular and Neuroendocrine Responses to Stress in Rats The Journal of Nutrition 133: 1921-1929 The American Society for Nutritional Sciences, June, 2003. Retrieved July 10, 2020.
- J.B. Johnson, D.R. Laub, and S. John, The effect on health of alternate day calorie restriction: eating less and more than needed on alternate days prolongs life Med Hypotheses 2006 67(2) (2006): 209-211. Retrieved July 10, 2020.
- J.B. Johnson, W Summer, R.G. Cutler, B. Martin, D.H. Hyun, V.D. Dixit, M. Pearson, M. Nassar, R. Tellejohan, S. Maudsley, O. Carlson, S. John, D.R. Laub, and M.P. Mattson, Alternate day calorie restriction improves clinical findings and reduces markers of oxidative stress and inflammation in overweight adults with moderate asthma Free Radic Biol Med. 42(5)(Mar 2007): 665-674. Retrieved July 10, 2020.
- Ira R. Byock, Patient Refusal of Nutrition and Hydration American Journal Hospice & Palliative Care March/April 1995. Retrieved July 10, 2020.
- H.M. Shelton. Fasting Can Save Your Life (American Natural Hygiene Society Inc.,  1991. ISBN 0914532235), 38-39, 160-163.
- Shelton, 107-113.
- Shelton, 122-124.
- Adamson, Eve, and Linda Horning. The Complete Idiot's Guide(R) to Fasting. Alpha, 2002. ISBN 978-0028643274
- Burke, Deirdre. Food and Fasting (Understanding Religions). Hodder Wayland, 1992. ISBN 978-0750204217
- Chatham, Romara Dean. Fasting: A Biblical Historical Study. Bridge-Logos Publishers, 1987. ISBN 978-0882707693
- Fuhrman, Joel. Fasting and Eating for Health: A Medical Doctor's Program for Conquering Disease. St. Martin's Griffin, 1995. ISBN 031218719X
- Grimm, Veronika. From Feasting To Fasting: The Development of Early Christian Ascetism. Routledge, 1996. ISBN 978-0415135955
- Rogers, Carole Garibaldi. Fasting… Exploring A Great Spiritual Practice. Sorin Books, 2004. ISBN 978-1893732643
- Shelton, H.M. Fasting Can Save Your Life. Tampa, FL: American Natural Hygiene Society Inc., 1991. ISBN 0914532235
All links retrieved July 10, 2020.
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