How to Grow in Fasting

Fasting is not just “not eating”

The simplest definition is also the most misleading: fasting would be abstaining from food. This is materially true, but the definition misses the essential. A dietitian who skips a meal, a protester on hunger strike, an athlete watching their weight are not fasting in the Christian sense—they deprive themselves, but for themselves. Christian fasting is distinguished from all other deprivation by its end: it is directed toward God. It is a deprivation offered, and it is the offering, not the deprivation, that makes it a religious act.

Saint John Chrysostom already warned his faithful that fasting from bread without fasting from sin is a mutilated fast: "Do you fast? Prove it by your works," he said^[2]—what good is it to deprive the stomach if the tongue devours one's neighbor through slander? True fasting is not primarily a matter of the stomach but of the heart: it begins at the table, but it aims higher.

Fasting, abstinence, mortification: distinguishing the terms

Three similar words are often confused. It is worth distinguishing them, for the Church's discipline is based on this distinction.

Fasting and abstinence are thus two particular and codified forms of mortification, that broader word which refers to all that we "put to death" in ourselves to make room for God. This is why spiritual masters speak interchangeably of fasting and mortification: fasting is mortification made concrete in the most everyday, universal, and humble place—the table. For the more radical interior renunciation that cuts at the root of attachment to goods, see How to grow in detachment.

A universal practice transfigured by Christ

Fasting is not a Christian invention. All religions and all wisdom traditions have known it: people fast to purify the body, to implore heaven, to mourn, to prepare for a trial. Saint Basil liked to remind us that fasting is as old as the world: the very first law given to man in paradise was a fast—"you shall not eat" of the forbidden fruit (Gn 2:17). Humanity fell through a disordered meal; it rises again through fasting^[3].

But Christ transfigured this ancient practice. He did not abolish it: he interiorized it. Where fasting risked becoming a bargaining chip with God or a display of piety, Jesus sent it back to the secret of the heart (Mt 6:16-18) and linked it to the nuptial joy of his presence (Mt 9:15). Christian fasting, therefore, is not a deprivation aimed at performance or health: it is an act of love that prepares for the encounter with the Bridegroom.

Before seeking how to grow in fasting, we must know why we fast—otherwise, we risk disciplining ourselves for the wrong reasons. Saint Thomas Aquinas, in the question he devotes to fasting, admirably summarizes the three purposes that the Church has always recognized. Fasting, he writes, is an act of virtue when practiced for one of these three reasons:

“Fasting is undertaken mainly for three reasons. First, to repress the desires of the flesh. […] Next, so that the spirit may rise more freely to the contemplation of heavenly things. […] Finally, to make satisfaction for sins.” — Saint Thomas Aquinas, Summa Theologica, II-II, q. 147, a. 1^[4]

These three purposes are not opposed to each other: they complement one another, and a single fast can aim at all of them. But distinguishing them helps us to fast rightly.

Repressing the Desires of the Flesh

The first purpose is the most immediate: fasting weakens the tyranny of appetites. An overfed body becomes heavy, sluggish, given over to its desires; a body held in check regains its docility. Saint Paul experienced this as an athlete: “But I treat my body harshly, I make it my slave, lest after proclaiming the Gospel to others I myself should be disqualified” (1 Cor 9:27)^[5]. Fasting is not hatred of the body: it is training the body, as one trains a horse—not to break it, but to make it useful. It is the dietary application of all temperance—see How to grow in temperance.

Raising the Spirit to God

The second purpose is higher, and it is what distinguishes Christian fasting from any mere diet. A full stomach weighs down the soul; an empty belly makes it light, watchful, available. The Desert Fathers observed this: sobriety sharpens prayer, just as hunger sharpens the senses. Fasting carves out in man a void that God comes to fill; it transforms a bodily need into a cry of the soul. This is why Scripture almost always associates fasting with prayer: we fast to pray better, and prayer gives fasting its meaning. For more on this prayer supported by fasting, see How to grow in prayer.

Repairing and Making Satisfaction for Sin

The third purpose is the most forgotten today, yet the most biblical: fasting repairs. It expresses repentance, it “does penance” in the strong sense, it offers God a small voluntary suffering in reparation for faults. When Nineveh learns of its condemnation, it does not argue: it fasts (Jon 3:5-10), and God relents. Fasting says to God, through the body, what words struggle to express: “I am sorry, I turn away, I return.” It is this dimension of satisfaction that is developed in the article on penance—see How to grow in penance—and in the article on offering up suffering, How to grow in reparation.

We do not grow in a practice by enduring it as a rule: we must rediscover its source. Now, fasting runs through the whole Bible, from Sinai to the Cross.

Returning to God “with All Your Heart”

In the Old Testament, fasting is the gesture of return. The prophet Joel, in the face of disaster, issues the call that sums up all biblical penance:

“And now—oracle of the Lord—return to me with all your heart, with fasting, with weeping, and with mourning! Tear your hearts and not your garments, and return to the Lord your God, for he is gracious and merciful, slow to anger and abounding in love, renouncing punishment.” — Joel 2:12-13^[6]

Everything is there: fasting has value only when it is related to the heart. “Tear your hearts and not your garments”—this phrase condemns in advance any purely external fast. The body that fasts must signify a heart that is converted; otherwise, it signifies nothing.

The True Fast According to Isaiah 58: Breaking Chains, Sharing Bread

The most striking text is that of Isaiah. The people fast and are surprised that God pays no attention. The divine response is thunderous: the fast that pleases God is not first of all that of the mouth, but that of hands that open.

“Is not this the fast that I choose: to loose the bonds of injustice, to undo the straps of the yoke, to let the oppressed go free, and to break every yoke? Is it not to share your bread with the hungry, and bring the homeless poor into your house?” — Isaiah 58:6-7^[7]

This text establishes the inseparability of fasting and almsgiving: the bread we do not eat must become the bread we give. A fast that fattens the bank account instead of feeding the poor is, according to Isaiah, a failed fast. We will find this iron law again later in Saint Peter Chrysologus. On the sharing that crowns fasting, see How to grow in almsgiving.

Jesus Fasts Forty Days

The New Testament opens, for the public life of Jesus, with a fast. Before proclaiming the Kingdom, Christ withdraws into the desert and fasts for forty days—echoing Israel’s forty years in the desert, Moses’ forty days on Sinai, and Elijah’s journey to Horeb.

“Jesus was led by the Spirit into the desert, where for forty days he was tempted by the devil. He ate nothing during those days, and when they were ended, he was hungry.” — Luke 4:1-2^[8]

It is in this hunger that the temptation comes—“If you are Son of God, command this stone to become bread”—and Jesus repels it with a word from Scripture: “Man does not live by bread alone” (Mt 4:4)^[9]. Christ’s fast is not an isolated ascetic feat: it is the model for all Christian fasting, which is always a combat against the tempter, supported by the Word of God. It is from these forty days that the Church has drawn the forty days of Lent.

“When You Fast”: The Teaching of Christ

Jesus never commanded his disciples not to fast; he commanded them to fast well. In the Sermon on the Mount, he places fasting, alongside almsgiving and prayer, among the three pillars of the new righteousness—and for all three, he denounces the same sickness: seeking the approval of men.

“And when you fast, do not look gloomy like the hypocrites: they disfigure their faces so that others may see that they are fasting. […] But you, when you fast, anoint your head and wash your face, so that your fasting may not be seen by others but only by your Father who is in secret.” — Gospel according to Saint Matthew 6:16-18^[10]

"When you fast," not "if you fast": Christ takes fasting for granted. What He corrects is not the practice, but the intention. The whole secret of growth in fasting is already here: to fast under the gaze of the Father alone.

“Then they will fast”: Fasting and the Bridegroom

A saying of Jesus is often invoked to downplay fasting; in reality, it establishes it. When people are surprised that His disciples do not fast, Jesus replies:

“Can the wedding guests mourn during the time when the Bridegroom is with them? But the days will come when the Bridegroom is taken away from them, and then they will fast.” — Gospel according to Saint Matthew 9:15^[11]

Here, fasting is linked to the felt absence of the Bridegroom. As long as Christ is visibly present, we rejoice; when He withdraws, we fast—not to punish Him for His absence, but to deepen our longing, to wait for Him, to hasten His return. Christian fasting is thus a fasting of nuptial expectation: it expresses our hunger for the One who is missing. This dimension of hope connects with How to grow in hope.

Fasting and Spiritual Combat: “This kind…”

Finally, fasting is a weapon. Faced with a demon the disciples cannot cast out, Jesus declares that “this kind can come out only by prayer”—and many manuscripts add: “and by fasting” (Mark 9:29)^[12]. Whether this detail is from the original text or from a very ancient tradition, it expresses a unanimous conviction of the Church: certain spiritual battles are won only through prayer and fasting. Fasting disarms the adversary by first disarming what, within us, gives him a foothold: gluttony, softness, attachment to comfort. For more on this vigilance of the spiritual combatant, see How to grow in spiritual vigilance.

If we were to remember only one rule for growing in fasting, it would be this: never fast alone. Not alone in the sense of isolated, but alone in the sense of separated from its two sisters—prayer and almsgiving. The Catechism presents them together as the three forms of conversion:

“Interior conversion urges expression of this attitude in visible signs, gestures, and works of penance. […] Scripture and the Fathers insist above all on three forms: fasting, prayer, and almsgiving, which express conversion in relation to oneself, to God, and to others.” — Catechism of the Catholic Church § 1434, citing Tobit 12:8 and Matthew 6:1-18^[13]

Fasting converts me in relation to myself (I detach from my belly); prayer converts me in relation to God; almsgiving converts me in relation to my neighbor. To separate fasting from the other two is to mutilate it. This is taught with unforgettable force by Saint Peter Chrysologus, in a passage the Church reads every Lent:

“There are three things, my brethren, on which faith stands firm, devotion remains constant, and virtue endures: prayer, fasting, and mercy. […] Prayer knocks at the door, fasting obtains, mercy receives. Prayer, mercy, fasting: the three are one and give life to each other. Indeed, fasting is the soul of prayer, mercy is the life of fasting. Let no one divide them; they cannot be separated.” — Saint Peter Chrysologus (c. 406-450), Sermon 43^[14]

“Fasting bears no fruit unless watered by mercy,” continues the holy bishop of Ravenna: “what rain is to the earth, mercy is to fasting.”^[15] This is why fasting that does not lead to sharing dries up, and prayer without fasting remains superficial. To grow in fasting is always to grow simultaneously in prayer and in charity—see How to grow in charity.

Many Catholics are unaware of what the Church still expects of them regarding fasting. The discipline has been lightened, not abolished; knowing it is the first step to growth, for one cannot grow in vagueness.

Days of Penance: Ash Wednesday, Good Friday, Fridays

Church law sets a minimal foundation, common to all. The following table summarizes what is obligatory today in the Latin Church.

The Catechism reminds us that these times are special moments willed by the Church for the conversion of all:

“The times and days of penance throughout the liturgical year (the season of Lent, each Friday in memory of the Lord’s death) are intense moments of the Church’s penitential practice. These times are particularly appropriate for spiritual exercises, penitential liturgies, pilgrimages as signs of penance, voluntary self-denial such as fasting and almsgiving.” — Catechism of the Catholic Church § 1438^[16]

Fasting and Abstinence: What the Law Actually Says

Ecclesiastical fasting does not mean eating nothing all day. In practice, in the current usage of the Latin Church, it allows one full meal, to which a little food may be added in the morning and evening, provided that together they do not equal a second meal. Abstinence refers to refraining from meat. These are intentionally modest minimums: the Church sets a low threshold so that it is manageable for all, leaving each person free, in generosity, to go further.

For Whom? Ages and Exemptions

Canon law specifies who is bound, and exempts those for whom fasting would be harmful:

• Abstinence is obligatory from age 14;
• Fasting is obligatory from 18 to 59 years old^[17].
• Exempted, by common sense and charity, are the sick, pregnant or nursing women, the elderly, manual laborers, and children — for fasting is ordered to the health of the soul, never to the ruin of the body.

This flexibility is not laxity: it is the application of the principle that discretion governs all asceticism. Fasting is not an end in itself; when it harms the charity owed to oneself or to others, it ceases to be virtuous.

From Ancient Fasting to Paenitemini: A Lightened, Never Abolished Discipline

There was a time when the Church imposed almost daily fasting throughout Lent, abstinence on all Fridays and many vigils, and long Eucharistic fasts. In 1966, by the apostolic constitution Paenitemini, Paul VI reformed this discipline: he reduced the strictly obligatory fast days to Ash Wednesday and Good Friday, while solemnly reaffirming the permanent duty of penance and the possibility for episcopal conferences to substitute other forms of penance or works of charity for meatless Fridays^[18].

This reform is often misunderstood. Paenitemini did not say: “you no longer need to do penance”; it said: “penance is not reduced to a list of forbidden foods; it is a daily duty, of which the Church sets only the minimum.” The danger of such a low minimum is that it may be mistaken for a maximum. Growing in fasting means precisely going beyond the minimum — not out of scrupulosity, but out of love.

At last comes the practical question. How does one move from a minimal, neglected, or imposed fast to a living fast that helps the soul grow? The saints agree on several very concrete paths.

Start Small, Persevere Over Time

The beginner’s first mistake is initial excess: one decides on a great heroic fast, lasts two days, collapses, and gives up. The Desert Fathers recommended the opposite: a small, regular renunciation is better than a great, unsustainable one. It is better to reclaim Friday fasting, to add a modest but faithful deprivation, than to aim for a feat that mainly feeds pride. Constancy is the key virtue here: see How to grow in perseverance. A fast that endures transforms; a spectacular but brief fast only inflates.

Fasting “in Secret”: Fleeing Vainglory

The second path is the one Christ traced: secrecy (Mt 6:17-18). Fasting is the food of the hidden life. As soon as it is displayed — by complaining, by hints, by a gloomy face — it has already received its reward and lost its value. Growing in fasting means learning to hide it from view: do not talk about it, do not complain, keep a joyful face. This discretion protects against the greatest danger of fasting, spiritual pride, against which humility keeps watch — see How to grow in humility.

From Fasting of the Mouth to Fasting of the Eyes and Tongue

Fasting matures by expanding. Fasting from food is only the entryway; beyond it opens a whole art of voluntary deprivation that touches the other senses and appetites. Saint Augustine and the whole tradition speak of a fast of the eyes (what we look at), of the tongue (gossip, idle talk, complaining), of the ears, of judgment. In the age of screens, this broader fast takes on new significance: fasting from information, entertainment, notifications is often a more demanding — and more liberating — mortification than fasting from a meal. The criterion remains the same: we give up something good to make room for something far better.

Linking Fasting to Prayer and Almsgiving

As we have seen: a fast done in isolation withers. The royal road to growth is therefore to tie each fast to a time of prayer and an act of almsgiving. The meal skipped becomes a concrete alms: the money saved goes to the poor. The hunger felt becomes a reminder that prompts prayer: every pang of the stomach is an inner bell saying, “remember God.” Thus fasting ceases to be an endured emptiness and becomes a springboard: it propels us toward prayer and toward our neighbor. This is exactly the pedagogy of Saint Peter Chrysologus cited above.

Offering One’s Hunger: From Renunciation to Love

The summit of growth in fasting is offering. As long as I fast to master myself or to purify myself, I remain at the center. Mature fasting shifts this center: I no longer offer just a dish, I offer my hunger—this small suffering—in union with Christ’s hunger in the desert and His thirst on the Cross, for sinners, for souls, for the world. Deprivation then becomes a prayer of intercession and reparation. Saint John Cassian, in the 4th century, nevertheless warned against the inversion of values: fasting is never the goal, but the means.

In substance, Saint John Cassian (c. 360-435), in the first of his Conferences, teaches that a rigorous fast does not make up for the harm done by a movement of anger: secondary exercises—fasts, vigils, retreat, meditation on the Scriptures—must be ordered to the principal goal, purity of heart, that is, charity^[19].

Fasting is a means; charity is the end. A rigorous fast accompanied by a hard heart is a contradiction; a small fast offered out of love is worth a thousand dry heroics. For more on this purity of heart, which is the goal, see How to grow in purity of heart.

Like any virtue, fasting can go astray in two opposite directions. Knowing them helps us keep to the middle path.

Pharisaism: Fasting for Oneself

The first pitfall is the one Jesus most strongly opposed: fasting to be seen, or worse, fasting while despising those who do not fast. This is the Pharisee in the parable, standing in the Temple: “I fast twice a week” (Lk 18:12)^[20]—and who leaves unjustified, because his fasting has fed his pride. Fasting, the spiritual good par excellence, thus becomes the occasion for the most spiritual sin: vainglory. The remedy is secrecy and humility: to know oneself as a sinner who fasts, not as someone just because one fasts.

Indiscretion: When Asceticism Harms Charity or Health

The second pitfall is the opposite: asceticism without measure. Out of poorly guided generosity, one imposes excessive fasts that ruin health, make one irritable, incapable of working or serving—in short, that harm charity. Tradition calls this indiscretion. Spiritual masters, from Cassian to Saint Francis de Sales, are unanimous: a fast that makes you unbearable to others or harmful to your duties of state is a bad fast. Some saintly ascetics spoke very harshly about the body—but this heroic language should not obscure the common rule, which is discretion. Fasting must be governed by prudence: see How to grow in prudence. The golden rule: in doubt, and especially in case of fragile health, seek advice from a priest or spiritual director—see How to grow in spiritual direction.

How can we recognize a fast that truly helps us grow? By its fruits—not by its rigor.

Freedom and Lightness of Heart

The first fruit is freedom. The person who fasts regularly discovers himself less a slave: less captive to his cravings, habits, and comforts. He has learned that one can be hungry and survive, desire and not give in—and this experience makes him free far beyond the table. Fasting teaches the heart that it is not ruled by its appetites. It brings a lightness: one possesses oneself, and so one breathes.

Compassion for the Poor

The second fruit is compassion. One who has never been hungry voluntarily does not truly understand one who is hungry out of necessity. Fasting carves out in us a physical solidarity with the hungry of the world; it transforms a statistic into an experience. As Chrysologus said, the one who fasts “must sympathize with the man who is hungry, if he wants God to sympathize with his own hunger”^[21]. Fasting, far from turning us inward, opens our hands.

Hunger for God

The third and highest fruit is a hunger of another kind. By unlearning easy satiety, the soul discovers another thirst, which nothing earthly can satisfy. Fasting reveals that our true lack is not bread, but God. “Blessed are those who hunger and thirst for righteousness, for they shall be satisfied” (Mt 5:6): bodily fasting is the apprenticeship of this blessed hunger. It does not deprive us to impoverish us, but to make us capable of God, as Benedict XVI summed up:

“Fasting can help us to mortify our selfishness and open our hearts to the love of God and neighbor. […] The ultimate purpose of fasting is to help each of us, as the Servant of God John Paul II wrote, make a complete gift of self to God.” — Benedict XVI, Message for Lent 2009^[22]

The spirituality of the Divine Will, transmitted to the Servant of God Luisa Piccarreta (1865-1947)—a private revelation received within the Church but not declared supernatural (Nulla Osta of the Dicastery for the Doctrine of the Faith, June 2024, confirmed on 3 December 2024; the theological theses interpreting it do not commit the Magisterium)—gives fasting—and more broadly, mortification—its ultimate meaning. It does not remove the effort or the value, but reveals its true purpose: mortification is not an end in itself, it is the air that a healthy soul breathes.

Jesus tells Luisa that "mortification must be the air of the soul": "by the air the soul breathes, one can tell whether it is healthy or sick"—breathed in, mortification purifies and unifies everything in her; absent, everything in her becomes discordant^[23].

Fasting, in this light, ceases to be an exhausting struggle and becomes an ordinary breathing: not a heroic effort reserved for special seasons, but the steady breath of a unified life. Jesus further explains to Luisa that mortification is fruitful—not destruction, but purification that gives birth to virtues:

"My daughter, Mortification is like a fire that dries up all the bad humors in the soul and floods it with a humor of Holiness, giving birth to the most beautiful Virtues"^[24].

To grow in fasting, from this perspective, is not simply to tighten the reins a little more: it is to let the Will of God reorder desire from within, until renunciation is no longer a struggle but a peaceful gift. Human fasting, grafted onto the Divine Will, ceases to be a forced deprivation and becomes the calm of a heart no longer burdened by disorder. For more on this new life, see How to grow in abandonment to God.

We do not grow in a practice by setting it up as an abstract ideal, but by contemplating those who have lived it. Fasting has its supreme master: Christ, who fasted for forty days and made this fast the threshold of His mission. All of Jesus’ life holds these two aspects together: He fasted in the desert, but He also turned water into wine at Cana and shared so many meals that people called Him "a glutton and a drunkard" (Mt 11:19). His sovereign freedom—to fast or to feast according to God’s hour—is the measure of our own.

Behind Him, a cloud of witnesses: Moses and Elijah fasting for forty days; Anna the prophetess who "worshipped God night and day with fasting and prayer" (Lk 2:37)^[25]; the Desert Fathers, whose sobriety was their rule of life; Saint Anthony, Saint Basil, Saint John Chrysostom, Saint Francis of Assisi, Saint Catherine of Siena, and so many others for whom fasting became second nature. None of them fasted for the sake of fasting: all made hunger a path to God. It is to this company that fasting unites us.

Growing in fasting is not decreed in a single day; it is cultivated through small acts of fidelity. Concretely:

• Rediscover Friday. Before aiming for great fasts, restore the Friday penance—no meat, or another deprivation offered in memory of the Passion. This is the ordinary foundation, and many have forgotten it.
• Live Lent as a true time of fasting, not just as a symbolic “giving up chocolate.” Choose a real deprivation, sustainable for forty days, linked to prayer and sharing.
• Connect each fast to prayer and almsgiving. Decide in advance: what I do not eat, I give; the time I save, I spend in prayer.
• Fast in secret. Do not talk about it, do not complain, keep a joyful face.
• Seek advice in case of fragile health, scruples, or temptation to excess. Discretion is part of the virtue.
• Offer your hunger, finally, for someone: a loved one, a sinner, a soul in purgatory, the world. This is where fasting becomes love.

Fasting is not a chore from another age nor a performance for spiritual athletes: it is, in its very humility, one of the simplest and deepest ways to say to God, “I prefer You.” When the stomach learns to wait, the heart learns to desire; and when the heart desires God more than bread, then fasting has accomplished its work.

• How to grow in temperance — the cardinal virtue of which fasting is the dietary application: its nature, its parts, its fruits.
• How to grow in the fight against gluttony — the struggle against the vice opposed to sobriety at table.
• How to grow in penance and How to grow in reparation — the satisfactory and oblation dimension of fasting.
• How to grow in almsgiving — the inseparable sister of fasting: the bread we do not eat becomes the bread we give.
• How to grow in prayer — the prayer that fasting supports and lightens.
• How to grow in chastity and How to grow in purity of heart — other schools of mastery and transparency of heart.
• How to grow in detachment and How to grow in perseverance — cutting at the root, and persevering over time.