There is both a physical and a spiritual fast. In the physical fast the body abstains from food and drink. In the spiritual fast, the faster abstains from evil intentions, words and deeds. One who truly fasts abstains from anger, rage, malice, and vengeance. One who truly fasts abstains from idle and foul talk, empty rhetoric, slander, condemnation, flattery, lying and all manner of spiteful talk. In a word, a real faster is one who withdraws from all evil.
As much as you subtract from the body, so much will you add to the strength of the soul.
Holy Hierarch Basil the Great
Do you fast? Then feed the hungry, give drink to the thirsty, visit the sick, do not forget the imprisoned, have pity on the tortured, comfort those who grieve and who weep, be merciful, humble, kind, calm, patient, sympathetic, forgiving, reverent, truthful and pious, so that God might accept your fasting and might plentifully grant you the fruits of repentance.
Fasting of the body is food for the soul.
Holy Hierarch John Chrysostom
Whosoever rejects the fasts, deprives himself and others of weapons against his own much-suffering flesh and against the devil, who have power over us especially as the result of our intemperance.
Holy Righteous John of Kronstadt
The greatest of the virtues is prayer, while their foundation is fasting.
Holy Hierarch Ignaty Brianchaninov
If thou, O man, dost not forgive everyone who has sinned against thee, then do not trouble thyself with fasting. If thou dost not forgive the debt of thy brother, with whom thou art angry for some reason, then thou dost fast in vain God will not accept thee. Fasting will not help thee, until thou wilt become accomplished in love and in the hope of faith. Whoever fasts and becomes angry, and harbors enmity in his heart, such a one hates God and salvation is far from him.
Venerable Ephraim the Syrian
It is necessary most of all for one who is fasting to curb anger, to accustom himself to meekness and condescension, to have a contrite heart, to repulse impure thoughts and desires, to examine his conscience, to put his mind to the test and to verify what good has been done by us in this or any other week, and which deficiency we have corrected in ourself in the present week. This is true fasting.
Saint John Chrysostom
A excellent faster is he who restrains himself from every impurity, who imposes abstinence on his tongue and restrains it from idle talk, foul language, slander, condemnation, flattery and all manner of evilspeaking, who abstains from anger, rage, malice and vengeance and withdraws from every evil.
Saint Tichon of Zadonsk
Seest thou what fasting does: it heals illnesses, drives out demons, removes wicked thoughts, makes the heart pure. If someone has even been seized by an impure spirit, let him know that this kind, according to the word of the Lord, "goeth not out but by prayer and fasting" (Matthew 17:21).
Saint Athanasius the Great
By fasting it is possible both to be delivered from future evils and to enjoy the good things to come. We fell into disease through sin; let us receive healing through repentance, which is not fruitful without fasting.
Saint Basil the Great
The strictness of the Quadragesima [the Forty Days] mortifies the passions, extinguishes anger and rage, cools and calms every agitation springing up from gluttony. And just as in the summer, when the burning heat of the sun spreads over the earth, the northern wind renders a benefaction to those who are scorched, by dispersing the sultriness with a tender coolness: so fasting also provides the same, by driving out of bodies the burning which is the result of overeating.
Saint Asterius of Amasia
As bodily food fattens the body, so fasting strengthens the soul; imparting it an easy flight, it makes it able to ascend on high, to contemplate lofty things and to put the heavenly higher than the pleasant and pleasurable things of life.
Saint John Chrysostom
Fasting is the mother of health; the friend of chastity; the partner of humblemindedness (illnesses are frequently born in many from a disorderly and irregular diet).
Venerable Simeon, the New Theologian
Give the body as much food as it needs, and thou shalt receive no harm, even if thou shouldest eat three times a day. If a man eats but once a day, but undiscerningly, what benefit is there to him from that. The warfare of fornication follows excess in eating - and after this the enemy weighs down the body with sleep in order to defile it.
Saints Barsanuphius and John
As a flame of fire in dry wood, so too is a body with a full belly.
Venerable Isaac the Syrian
Always establish one and the same hour for taking food, and take it for fortifying the body and not for enjoyment.
Venerable Anthony the Great
Do not neglect the Forty Days; it constitutes an imitation of Christ's way of life.
Saint Ignatius the Godbearer
The point is not only that we should come to church each day, that we should continually listen to one and the same thing, and that we should fast for the whole Forty Days. No! If we, from continually coming here and listening to the teaching, do not acquire anything and do not derive any good for our soul from the time of the fast all this does not procure for us any benefit, but rather serves for our greater condemnation, when despite such concern for us by the Church we remain just the same as before.
Do not say to me that I fasted for so many days, that I did not eat this or that, that I did not drink wine, that I endured want; but show me if thou from an angry man hast become gentle, if thou from a cruel man hast become benevolent. If thou art filled with anger, why oppress thy flesh? If hatred and avarice are within thee, of what benefit is it that thou drinkest water? Do not show forth a useless fast: for fasting alone does not ascend to heaven.
Saint John Chrysostom
Let thy mind fast from vain thoughts; let thy memory fast from remembering evil; let thy will fast from evil desire; let thine eyes fast from bad sights: turn away thine eyes that thou mayest not see vanity; let thine ears fast from vile songs and slanderous whispers; let thy tongue fast from slander, condemnation, blasphemy, falsehood, deception, foul language and every idle and rotten word; let thy hands fast from killing and from stealing another's goods; let thy legs fast from going to evil deeds: Turn away from evil, and do good.
Saint Tichon of Zadonsk
The holy fasters did not approach strict fasting suddenly, but little by little they became capable of being satisfied by the most meagre food. Despite all this they did not know weakness, but were always hale and ready for action. Among them sickness was rare, and their life was extraordinarily lengthy.
To the extent that the flesh of the faster becomes thin and light, spiritual life arrives at perfection and reveals itself through wondrous manifestations, and the spirit performs its actions as if in a bodiless body. External feelings are shut off, and the mind that renounces the earth is raised up to heaven and is wholly immersed in the contemplation of the spiritual world.
Venerable Seraphim of Sarov
The more days of fasting there are, the better the healing is; the longer the period of abstinence, the more abundant the gain of salvation is.
We are told: It is no big deal to eat non-Lenten food during Lent. It is no big deal if you wear expensive beautiful outfits, go to the theater, to parties, to masquerade balls, use beautiful expensive china, furniture, expensive carriages and dashing steeds, amass and hoard things, etc. Yet what is it that turns our heart away from God, away from the Fountain of Life? Because of what do we lose eternal life? Is it not because of gluttony, of expensive clothing like that of the rich man of the Gospel story, is it not because of theaters and masquerades? What turns us hard-hearted toward the poor and even toward our relatives? Is it not our passion for sweets, for satisfying the belly in general, for clothing, for expensive dishes, furniture, carriages, for money and other things? Is it possible to serve God and mammon, to be a friend to the world and a friend to God, to serve Christ and Belial? That is impossible.
Why did Adam and Eve lose paradise, why did they fall into sin and death? Was it not because of one evil? Let us attentively consider why we do not care about the salvation of our soul, which cost the Son of God so dearly. Why do we compound sin upon sin, fall endlessly into opposing to God, into a life of vanity? Is it not because of a passion for earthly things and especially for earthly pleasures? What makes our hearts become crude? Why do we become flesh and not spirit, perverting our moral nature? Is it not because of a passion for food, drink, and other earthly comforts? How after this can one say that it does not matter whether you eat non-Lenten food during Lent? The fact that we talk this way is in fact pride, idle thought, disobedience, refusal to submit to God, and separation from Him.
Holy Righteous St. John of Kronstadt
Fasting is wonderful, because it tramples our sins like a dirty weed, while it cultivates and raises truth like a flower.
St. John Chrysostomos
The reason that fasting has an effect on the spirits of evil rests in its powerful effect on our own spirit. A body subdued by fasting brings the human spirit freedom, strength, sobriety, purity, and keen discernment.
St. Ignatiy Brianchaninov
True fasting lies is rejecting evil, holding one's tongue, suppressing one's hatred, and banishing one's lust, evil words, lying, and betrayal of vows.
St. Basil the Great
Fasts do not shorten a man's life. Venerable Symeon the Stylite lived for 103 years, Saint Cyril the Anchorite lived 108 years, Saint Alypius the Stylite 118, Venerable John the Silent 104 years, Anthony and Theodosius the Great for 105 years, Venerable Paul of Thebes 113, Paul of Komel 112, Venerable Macarius of Alexandria 100, Venerable Sergius of Radonezh 78, Venerable Cyril Belozersky 90, Macarius Zheltovodsky 95.
Fasting consists not just of eating rarely, but also of eating little. And not just in eating only one meal, but in not eating much. Foolish is the faster, who waits for a specific time [to eat a meal], but then at the time of the meal is completely consumed, body and mind, with insatiable eating.
In proportion to how the body of the faster becomes thin and light, so the spiritual life attains perfection and reveals itself in wonderful ways. Then the soul acts as if in an incorporeal body. Carnal feelings are shut off, and the spirit, released from the world, ascends to heaven and completely immerses itself in contemplation of the spiritual world.
Every day one should partake of just enough food to permit the body, being fortified, to be a friend and helper to the soul in performing the virtues. Otherwise, with the body exhausted, the soul may also weaken.