Where the body sets the limit
Water always, and never beyond a day without a doctor’s word.

What are the safe limits of fasting?
What it is
The body sets the limit of every fast, and the old rules knew it. A day without food is within the reach of most healthy adults; days without water are within no one's. The house's own lines are short. Water is never given up. A fast is not carried beyond a day without a doctor's word. And for some people there is no fast at all: anyone pregnant or nursing, under eighteen, old and frail, unwell, diabetic, on medicine, underweight or with a history of an eating disorder.
The teaching
As the Buddha's middle way, the desert elders and the Rule of St Benedict teaches it.
The middle way
The Buddha's first teaching begins with a warning about extremes. There are two, he told his first five companions, that one who has gone forth should not follow: devotion to the pleasures of the senses, which is low and unprofitable, and devotion to self-torment, which is painful, ignoble and unprofitable. Avoiding both, he had found the middle way, which leads to peace, to insight and to awakening. He had tried the second extreme himself, and named it a mistake.
Later he taught a monk named Sona, who had driven himself in practice until his feet bled, with the picture of a lute. Strings tuned too tight do not play, and strings too slack do not play either; only strings tuned to the middle make music. Effort, he said, is to be tuned the same way.
Discretion, the guard of every virtue
The desert monks fasted more than anyone, and they taught that fasting without discernment does harm. In Cassian's Conferences the elders gather to ask which virtue keeps a monk from falling; some name fasting, some vigils, some solitude, and Antony answers discretion, the gift of judging the measure, because it keeps a person from both extremes. Excess, the elders say, does as much damage as neglect.
Antony's own saying is short: some have worn out their bodies with asceticism, but because they had no discernment, they are far from God.
The daily measure
In place of long fasts followed by feasting, the elders counselled a small and steady measure. Cassian describes the rule of the Egyptian monks: eat every day, a little, and rise from the table still a little hungry, rather than going without for days and then eating too much. A moderate fast kept daily, he says, is better than a severe one kept now and then, because the body stays strong enough to pray and to work.
Benedict's measure
Benedict's Rule sets the measure for a whole community, and sets it with mercy. It allows two cooked dishes at the main meal, so that one who cannot eat the first may eat the second, with a pound of bread a day and more when the work is heavy; less for children; and for the sick, meat and whatever else they need. The abbot is to fit everything to the weak and to the season.
In Lent a monk may offer something more of his own will, a little less food, sleep or talk, but only with the abbot's blessing, because an offering made without it is reckoned presumption and vainglory.
Love before the fast
The elders also taught that love comes before the fast. Cassian tells of an old monk who broke his fast to eat with visiting brothers, and explained: fasting is always with me, but you I cannot keep with me always. The guest was received as Christ, and the fast waited.
And the fast is hidden. Jesus tells those who fast to wash their faces and look as on any other day, so that no one sees it but God. A fast kept to be admired, the elders say, feeds the very pride it was meant to starve, and it is better to eat humbly than to fast proudly.
The body's own signals
The old rules and the house's own lines come to the same thing: the body sets the limit, not the will. Water is never given up. A fast is not carried beyond a day without a doctor's word. It is kept on a day without heavy work or long driving, and it ends at once at faintness, dizziness, a pounding heart, shaking or confusion, with a drink and a small plain meal.
Hunger that is only appetite can be watched with interest; hunger that has become weakness is a warning, and is obeyed.
Those who keep no fast
For some people there is no fast at all: anyone pregnant or nursing, under eighteen, old and frail, unwell, diabetic, on medicine, underweight, or with a history of an eating disorder. The faiths agree in their own exemptions, and none of them asks a person to harm the body. For such a person the discipline is found elsewhere: in silence, in a kept promise, in a meal eaten slowly and with thanks.
The gentlest form
For a healthy adult the mildest form is enough: the ordinary gap overnight, kept with water, ending in an ordinary breakfast eaten slowly. Or a plain meal in place of a rich one, as the monks kept their table. The point is to notice appetite and habit, the hand that reaches for food when the body is not hungry, and to give thanks for what is there, never to prove how much hunger can be borne.
If food or the body has become a fear, the step to take is not a fast but a word with a doctor.
How it is practised
For a healthy adult the mildest form is enough: the ordinary gap overnight, with water always and ordinary eating afterwards. Anyone the house has just named keeps no fast at all. It is kept on a day without heavy work or long driving, and it ends at once at faintness, a pounding heart or confusion. The point is to notice appetite and habit, never to prove how much hunger can be endured. If food or the body has become a fear, the step to take is not a fast but a word with a doctor.
Where it comes from
The traditions learned these limits the hard way. The Desert Fathers told stories against monks who fasted to be admired, and praised the one who broke his fast to eat with a guest. Simeon the stylite stood for decades on a pillar near Aleppo, medieval penitents wore the hair shirt, and the Flagellants of 1349 scourged themselves from town to town until the pope condemned them: history to read, and no model. The Buddha gave up his austerities after they brought him near death. Benedict's Rule allows more food for the sick and for heavy work. In 1944 and 1945 Ancel Keys studied thirty-six volunteers on half rations for six months: they grew weak, cold, low in mood and unable to think of anything but food.
What is known, and what is not
The physiology is well understood: the body turns from stored sugar to fat within about a day, and going without water becomes dangerous within days. Trials of timed eating find weight loss about equal to eating less in the ordinary way. The Minnesota study documented the mental cost of long hunger. Asceticism has not been shown to add years or to cleanse the body, and fasting can start or hide an eating disorder. Breatharianism, the claim to live without food, has never survived a supervised test; deaths have been reported among people attempting it, and it can kill.
Its words
- Asceticism
- Voluntary restraint in food, speech, sleep or comfort, taken on as training for a spiritual or moral end. From the Greek for an athlete's exercise.
- Desert Fathers
- The Christian monks of the Egyptian, Syrian and Palestinian deserts from the late third century, teachers of fasting, silence and watchfulness.
- Stylite
- A pillar saint: a Christian hermit of late antiquity, first in Syria, who spent years on a railed platform at the top of a column, in sight of the crowds below.
- Hair Shirt
- A rough shirt of goat hair, also called a cilice, that penitents once wore hidden under their clothes. Now a figure of speech for needless self-punishment.
- Flagellants
- Bands of lay penitents who whipped themselves in public procession, in Italy in 1260 and across central Europe in 1349, until the pope condemned them.
- Breatharianism
- The claim that a person can live on air or light without food. No test has borne it out, deaths have been reported among people attempting it, and it can kill.
Ask the Oracle further
Who should never try fasting at all, and am I one of them?What did the Minnesota starvation study show about fasting for too long?
Before you practise
Never go without water, and do not fast beyond a day without a doctor’s word; not at all if you are pregnant, under eighteen, diabetic, on medicine, underweight or have had an eating disorder. Never give up sleep for a practice, never enter cold water alone, and never stare at the sun. If food or your body has become a fear, please tell a doctor.
Its other branches
Fasting in the religionsSilenceCold and the vigilTraining the willThe whole artSearch the tree

