The Holy Fathers recommend 'moderate' fasting; one ought not to allow the body to be weakened too much, for then the soul, too, is harmed. Nor ought one to undertake fasting too suddenly; everything demands practice, and each one should look to his own nature and occupation. To choose among different kinds of food is to be condemned; all food is God-given, but it is advisable to avoid such kinds as add to the body's weight and appetite; strong spices, meat, spirituous drinks and such foods as are solely for the palate's enjoyment. For the rest, one may eat what is cheap and most easily available, they say. But by 'moderate' they mean one meal a day, and that one light enough not to fill the stomach to satiety.
The spiritual discipline of fasting is a tool for shifting the focus away from us and toward the Lord and our brothers and sisters in whom we encounter Him each day. If we distort fasting into a private religious accomplishment to prove how holy we are, we would do better not to fast at all. That would simply be a way of serving ourselves instead of God and those who bear His image and likeness. In Lent, our focus must be set squarely on Christ and His living icons, not on us. The fundamental calling of the Christian life is to become like our Lord, Who offered Himself up for the salvation of the world purely out of love. If we are truly in communion with Him, then we too must offer up ourselves for our neighbors. And as He taught in the parable of the Good Samaritan, there are no limits on what it means to be a neighbor to anyone who is in need, regardless of nationality, culture, or anything else. Those who limit their concern for people according to such standards place serving the kingdoms of this world before fidelity to the Kingdom of God.
First of all it must be understood that it is the duty of all Christians - especially of those whose calling dedicates them to the spiritual life - to strive always and in every way to be united with God, their creator, lover, benefactor, and their supreme good, by whom and for whom they were created. This is because the center and the final purpose of the soul, which God created, must be God Himself alone, and nothing else - God from whom the soul has received its life and its nature, and for whom it must eternally live. For all visible things on earth which are lovable and desirable - riches, glory, wife, children, in a word everything of this world that is beautiful, sweet, and attractive - belong not to the soul but only to the body, and being temporary, will pass away as quickly as a shadow. But the soul, being eternal by its nature, can attain eternal than all beauty, sweetness, and loveliness, and He is its natural home, whence it came and whither it must return. For as the flesh coming from the earth returns to the earth, so the soul coming from God returns to God and dwells in Him. For the soul was created by God in order to dwell in Him forever; therefore in this temporary life we must diligently seek union with God, in order to be accounted worthy to be with Him and in Him eternally in the future life.
For by prayer we obtain the divine favor, by fasting we extinguish the concupiscences of the flesh, by almsgiving sins are redeemed (Dan. iv. 24); and by all three together, the image of God is renewed in us, provided that we are ever ready in His praise, eager without ceasing for our own purification, and disposed at all times to assist our neighbor.
People have to answer greatly for not keeping the rules of the Church with respect to the fasts. People justify themselves by saying that they never considered it a sin to eat dairy products during the fasts. They repent and consider themselves sinners in every other respect, but they do not think to repent about not keeping the fasts. Meanwhile, they are transgressing the commandment of our holy Mother, the Church, and according to the teaching of the Apostle Paul, they are as the heathen and publicans because of their disobedience.
Fasting is beneficial when it is undertaken for quelling desire, humbling the soul, transforming hatred, extinguishing anger, erasing remembrance of wrongs, and for the purity of the understanding and the practice of prayer.
All the pleasers of God are like the angels in their love and devotion. They, just as the angels, waged war against the dark forces, and became strengthened in love of God. All of the prophets of the Old Testament lived in such a struggle. Godlessness prevailed, the Law of God was forgotten. The world persecuted them because they interfered with its sinful life. They hid in the 'depths of the earth.' The world hated them. The prophet Isaiah was sawed in two by a wooden saw, the prophet Jeremiah was trampled in a swamp. And in such surroundings they stood fast in faith and devotion. All righteous ones were sorrowful in the world because they were strangers to the sinful world. All of the apostles suffered in one way or another. Righteous men left for the desert. What made them saints? Suffering? Not suffering alone makes saints, but striving towards God, love of God, and the labor of overcoming obstacles to holiness, which is the fruit of man's labor and the gift of the Holy Spirit.
Restrain the excitable power of your soul by love; mortify the desiring power by self-mastery; give wings to the thinking power by prayer, and the light of your mind will never be dimmed.
Almsgiving heals the soul's incensive power; fasting withers sensual desire; prayer purifies the intellect and prepares it for contemplation of created beings. For the Lord has given us commandments which correspond to the powers of the soul.
No satiety has brought forth prudent behavior; for it is in the nature of fire to consume matter. And a filled stomach expels refined thoughts; it is the tendency of opposites to oppose each other.
Fasting was of no benefit to that Pharisee in the Gospel, even though he always fasted two days a week, because he had adulterated it with pride and condemnation of his neighbor (Luke 18:11-12). Not that this means fasting is unprofitable. Moses, Elijah & the Lord Himself showed how beneficial it is for those who fast properly in a way pleasing to God.