Saint Augustine's Prayer Book defines "Fasting, usually meaning not more than a light breakfast, one full meal, and one half meal, on the forty days of Lent."[45] Abstinence, according to Saint Augustine's Prayer Book, "means to refrain from some particular type of food or drink. One traditional expression of abstinence is to avoid meat on Fridays in Lent or through the entire year, except in the seasons of Christmas and Easter. It is common to undertake some particular act of abstinence during the entire season of Lent. This self-discipline may be helpful at other times, as an act of solidarity with those who are in need or as a bodily expression of prayer."[46]

Fasts may last for varying lengths of time -- one day, three days, seven days, and more. We should prayerfully seek the Lord about the length of our fast. Fasting should have an object in mind; we should have a clear idea of the need and purpose. One of the most pressing reasons for Christian fasting may be revival -- “Will you not revive us again...” (Psalm 85:6).
Medical supervision is recommended for any fast over three days. Most alternative medicine practitioners, such as homeopaths, naturopathic doctors, and ayurvedic doctors, can supervise and monitor patients during fasts. Those performing extended fasts and those with health conditions may require blood, urine, and other tests during fasting. There are many alternative health clinics that perform medically supervised fasts as well. Some conventional medical doctors may also supervise patients during fasts. Costs and insurance coverage vary, depending on the doctor, clinic, and requirements of the patient.
And there are many plans, because there are many schools of thought about what’s considered fasting, what food or drink should be consumed during eating windows, and how long these windows should last. Here are a few of the most common methods: Intermittent fasting means eating normally four or five days a week and consuming minimal calories on two or three nonconsecutive days. Time-restricted eating requires setting a window for consuming food, such as 7 a.m. to 7 p.m, and having nothing but noncaloric liquids the rest of the time. The “fasting mimicking diet” involves eating a small number of calories daily for a specific period of time — say five consecutive days every other month. These protocols all have benefits and drawbacks. One approach may work well for some while being entirely unsustainable for others.
Many people who want to try IF choose the 16:8 method because it allows you to eat whatever you want for an 8-hour window and then fast for 16 hours. During the fasting period, you can drink water, tea, coffee, and even diet soda. The trick is to figure out what 8-hour eating window works best for you. Are you fine with skipping breakfast? Or do you work out in the morning and prefer to forgo dinner? Experiment with the eating and fasting intervals that work best for you. However, like all restrictive diets, there are some drawbacks. For one, drinking caffeinated drinks while fasting can disrupt your circadian rhythm, and therefore, your metabolism.

Fasting helps you build a better brain, too. Intermittent fasting increases a protein in your brain called BDNF that researchers have nicknamed “Miracle-Gro for your brain.”[7] BDNF improves learning and memory and can help you forge stronger neural pathways, making your brain run faster and more efficiently, which is especially important as you age.
There are many promises God makes in His Word in regard to the blessings we will receive through prayer and fasting. In my book The Power of Prayer and Fasting, I talk about seven specific promises. I want to mention three of them here that I trust will bless you as you read. I have seen each of these promises come true in my walk with God, and I’m confident they also can live in you, through you, and will be yours as you call on God to do His will in your life.
Based on my experience, 24-hour fasts will get me into ketosis much faster than other methods like the fat fasting technique. To make the fast easier, I generally start my fast about 3–4 hrs before I go to bed the night before your full day fast. That means if I am going to fast all day Sunday, I start the fast on Saturday night right after my final meal. That way when I wake up, I am 11–12 hrs into my fast.
You’ll spike your blood sugar when you eat. If you’re fasting on a high-carb diet and you’ve powered through the cravings and lack of energy from low blood sugar, there’s a good chance you’ll eat a ton of carbs when you feast. You want to eat big meals when you fast to make sure you’re getting enough calories, but all those excess carbs in one go will spike your blood sugar in the opposite direction, from low to high.[14] High blood sugar causes fatigue and lack of focus. That raging hunger will also cause you to binge unnecessarily, and whatever carbs you don’t use will get stored as fat.
Fasting during religious festivals is also very common. Common examples are Maha Shivaratri (Most people conduct a strict fast on Maha Shivratri, not even consuming a drop of water ), 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 practised in some parts 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. In the fifth month (Shravan Maas) of the Hindu calendar, many celebrate Shraavana. During this time some will fast on the day of the week that is reserved for worship of their chosen god(s), while others will fast during the entire month.[82]
In a paper published in 2002 on the pseudo-experiment, Walford and colleagues reported that the Biosphere staff had been in excellent health. Nearly all of them lowered their blood pressure, blood sugar, cholesterol and other health measures. Still, their skeletal appearance was shocking. “They were malnourished, and they didn’t look healthy,” says Eric Ravussin, a metabolic researcher at the Pennington Biomedical Research Center in Baton Rouge, Louisiana.
Fasting is an ancient practice sparking new interest in both pop and scientific culture. Entrepreneurs, venture capitalists and a variety of celebrities have extolled its virtues in helping them lose weight, while medical experts are intrigued by the possibility that it may enhance cognitive functioning and longevity and help treat and prevent some diseases.
Hunger suppression. A ketogenic diet suppresses hunger, too.[16] On a keto diet, your liver turns fat into little bundles of energy called ketones, which it then sends through your bloodstream for your cells to use as fuel. Ketones suppress ghrelin, your body’s main hunger hormone.[17] High ghrelin makes you hungry. On keto, your ghrelin stays low, even when you don’t have food in your system. In other words, you can go longer without eating and you won’t get hungry. Fasting becomes significantly easier on keto so you can fast for longer windows to reap all the benefits.
Fasting helps you build a better brain, too. Intermittent fasting increases a protein in your brain called BDNF that researchers have nicknamed “Miracle-Gro for your brain.”[7] BDNF improves learning and memory and can help you forge stronger neural pathways, making your brain run faster and more efficiently, which is especially important as you age.
American King James Version×), which was portrayed in type by the Azazel goat on Atonement (Leviticus 16:20-22 Leviticus 16:20-22 20 And when he has made an end of reconciling the holy place, and the tabernacle of the congregation, and the altar, he shall bring the live goat: 21 And Aaron shall lay both his hands on the head of the live goat, and confess over him all the iniquities of the children of Israel, and all their transgressions in all their sins, putting them on the head of the goat, and shall send him away by the hand of a fit man into the wilderness: 22 And the goat shall bear on him all their iniquities to a land not inhabited: and he shall let go the goat in the wilderness.
Among the Western religions, only Zoroastrianism prohibits fasting, because of its belief that such a form of asceticism will not aid in strengthening the faithful in their struggle against evil. The other Western religions—Judaism, Christianity, and Islam—emphasize fasting during certain periods. Judaism, which developed many dietary laws and customs, observes several annual fast days, primarily on days of penitence (such as Yom Kippur, the Day of Atonement) or mourning. Christianity, especially Roman Catholicism and Eastern Orthodoxy, has observed a 40-day fast period during Lent, a spring period of penitence before Easter, and during Advent, a penitential period before Christmas. Among Roman Catholics the observance has been modified since the Second Vatican Council (1962–65) to allow greater individual choice, with mandatory fasting only on Ash Wednesday and Good Friday during Lent. Protestant churches generally leave the decision to fast to individual church members. The month of Ramadan in Islam is a period of penitence and total fasting from dawn to dusk.
View fasting as a response instead of a request. Don’t use fasting as a way to try to get the results you want from your prayers. Adding fasting to your requests to God when you want to convince Him to answer your prayers in a certain way amounts to using fasting as a manipulative tool. Instead of fasting to try to get God to respond to you, fast to respond to God. When you notice God at work in a special way in your life, you can express your awe, gratitude, and love back to Him by fasting. In the process, you may experience God’s presence on a deeper level. But fasting doesn’t guarantee any particular results. Fasting is simply a natural, inevitable response of a person to a grievous sacred moment in life – a moment when focusing on the physical pleasures of eating pales in comparison to focusing on the spiritual reality you’re encountering. Rather than fasting for what you can get from God, fast for what you can give to God. Fasting is simply a way of worshipping Him.
You’re consuming less food and thus spending less money. Rather than overeating to put on 1 pound of muscle and 4 pounds of fat in a week or two, you’re aiming to eat exactly enough to put on 1 pound of muscle without adding much fat on top of it.  Yeah, it’s a delicate balance, but there’s far less swing involved. You are just slowly, steadily, and consistently building muscle and strength over many months.
Add fasting to your church’s calendar. Throughout each year, schedule some time for your church’s congregation to fast to respond to different purposes, such as commemorating the major events in Jesus’ life or dealing with serious issues facing the world (poverty, abuse, the environment, the economy, wars, etc.). Encourage people in your church to fast before they’re baptized, and join with others in your congregation to fast before celebrating Communion. Also, remember to fast together regularly for repentance whenever God leads you all to do so.
^ Jump up to: a b c Harris, L; Hamilton, S; Azevedo, LB; Olajide, J; De Brún, C; Waller, G; Whittaker, V; Sharp, T; Lean, M; Hankey, C; Ells, L (February 2018). "Intermittent fasting interventions for treatment of overweight and obesity in adults: a systematic review and meta-analysis". JBI Database of Systematic Reviews and Implementation Reports. 16 (2): 507–547. doi:10.11124/JBISRIR-2016-003248. PMID 29419624.
The trial, which aimed to investigate how food deprivation affects the aging process, involved 218 normal and slightly overweight men and women between the ages of 21 and 51. Of the group, 143 of them were tasked with following CR, eating 25 percent fewer calories than usual — a decrease deemed feasible based on animal studies. They were to keep this regimen for two years with help from a behavioral intervention team and dietitians to make sure they were getting basic nutrition.
You’ll spike your blood sugar when you eat. If you’re fasting on a high-carb diet and you’ve powered through the cravings and lack of energy from low blood sugar, there’s a good chance you’ll eat a ton of carbs when you feast. You want to eat big meals when you fast to make sure you’re getting enough calories, but all those excess carbs in one go will spike your blood sugar in the opposite direction, from low to high.[14] High blood sugar causes fatigue and lack of focus. That raging hunger will also cause you to binge unnecessarily, and whatever carbs you don’t use will get stored as fat.

The physiology of fasting has been widely studied and documented by medical science. Beneficial effects such as lowered cholesterol and improved general functioning have been shown. Fasting as a treatment for illness and disease has been studied less, although some studies around the world have shown beneficial results. A 1984 study showed that workers in Taiwan who had severe chemical poisoning had dramatic improvement after a ten-day fast. In Russia and Japan, studies have demonstrated fasting to be an effective treatment for mental illness. Fasting has been featured on the cover of medical journals, although mainstream medicine has generally ignored fasting and detoxification treatments as valid medical procedures.

On Wednesday and Friday of the first week of Great Lent the meals which are taken consist of xerophagy (literally, "dry eating") i.e. boiled or raw vegetables, fruit, and nuts.[47] In a number of monasteries, and in the homes of more devout laypeople, xerophagy is observed on every weekday (Monday through Friday) of Great Lent, except when wine and oil are allowed.
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