The history of fasting and abstaining from particular foods is very extensive, going back to Old Testament times. For most of church history, fasting and abstinence was a regular feature of Christian life.
Mosaic law prescribed fasting on the Day of Atonement (Lev. 16:29-34, Numb. 29:7). Four further days of fasting were added after the Exile. Christ fasted (Mt 6.16; Mk 2.20; 9.29), as did the apostles (Acts 13:2; 14:23; 2 Cor 2:27).
The Didache tells us that the earliest Christians fasted on Wednesday and Friday. There was abstinence from some foods such as flesh meat. In both East and West, Friday abstinence was tied to remembrance of the death of Jesus Christ. Fasting and abstinence customs varied regionally and across church history.
Around 400, the Western church removed the Wednesday fast and moved to fasting on Friday and Saturday – i.e., leading up to Sunday Eucharist. There were vigil fasts before great feasts. Over the course of the Middle Ages, the time of breaking the fast moved from sunset or Vespers to the earlier hour of None in midafternoon, or to noon. As this caused a burden for those working the rest of the day without eating, by the 14th century a light meal of bread, vegetables, or fruit was taken at the end of day. In the 16th century a very light breakfast of not more than about two ounces was permitted, with about eight ounces of solid food in the evening.
Fasting also meant abstinence from some types of food, such as meat and meat products. On other days, there was abstinence without fasting. In the early church, abstinence was from meat, meat products, milk, eggs, butter, and cheese. In Carolingian times, milk, eggs, and milk products were permitted either by custom or repeated dispensation.
In the Eastern Church, days of fasting and abstinence have been numerous – as high as 180 days per year in the Greek Church.
Until 1917, general law of the Western Church required fasting on every day of Lent except Sunday; on Wednesday, Fridays, and Saturdays of the Ember weeks; and on the vigils of Christmas, Pentecost, Assumption, and All Saints. Fasting on Wednesdays and Fridays of Advent was customary in many places. Fasting meant taking only one meal a day and abstinence from meat, eggs, and milk products. Abstinence without fast was observed every Friday and Saturday of the year.
There were frequent dispensations from all this. A council at Baltimore in 1837 dispensed from the fast on Wednesdays and Fridays of Advent. Over the course of the 19th century, a dispensation from Saturday abstinence eventually became universal in the U.S. In 1886 Leo XIII allowed meat, eggs, and milk products on Sundays of Lent and at the main meal on every weekday except Wednesday and Friday in the U.S. Holy Saturday was not included in the dispensation. A small piece of bread was permitted in the morning with coffee, tea, chocolate, or a similar beverage.
In 1941 Pope Pius XII allowed bishops worldwide to dispense entirely from fast and abstinence except on Ash Wednesday and Good Friday, provided that there was abstinence from meat every Friday, and fast and abstinence on these two days and the vigil of the Assumption and Christmas. Eggs and milk products were permitted at breakfast and in the evening.
Until 1951, the workingmen’s privilege allowed the U.S. bishops to permit meat for any laborer –and his family – if abstinence would be difficult.
In 1951 the U.S. bishops standardized regulations calling for complete abstinence from meat on Fridays, Ash Wednesday, the vigils of Assumption and Christmas, and Holy Saturday morning for everyone over age seven. On the vigils of Pentecost and All Saints, meat could be taken at just one meal. Fast days, applying to everyone between 21 and 59, were the weekdays of Lent, Ember days, and the vigils of Pentecost, Assumption, All Saints, and Christmas. On these fast days only one full meal was allowed, with two other meatless meals permitted which together did not make up one full meal. Eating between meals was not permitted, with milk and fruit juice permitted. Health or ability to work exempted one.
In 1956, Holy Saturday became a day only of fasting and not of abstinence. The vigil of All Saints was no longer either. In 1957, fasting and abstinence on the vigil of the Assumption was transferred to the vigil of the Immaculate Conception. In 1959, Pope John XXIII permitted transferring the Christmas Eve fast and abstinence from December 24th to the 23rd.
The Second Vatican Council decreed in the liturgy constitution Sacrosanctum Concilium,
110. During Lent penance should not be only internal and individual, but also external and social. The practice of penance should be fostered in ways that are possible in our own times and in different regions, and according to the circumstances of the faithful; it should be encouraged by [by regional authorities and episcopal conferences].
Nevertheless, let the paschal fast be kept sacred. Let it be celebrated everywhere on Good Friday and, where possible, prolonged throughout Holy Saturday, so that the joys of the Sunday of the resurrection may be attained with uplifted and clear mind.
In 1966, immediately after the Second Vatican Council, Paul VI placed the emphasis on the interior and religious character of penitence, which is done by prayer, fasting, and charity. The U.S. bishops provided for abstinence from meat on the Fridays of Lent the same year. The 1983 Code of Canon Law minimally requires fasting and abstinence on Ash Wednesday and Good Friday, with conferences of bishops determining further regulations.
This review shows that historically, the rhythm of the liturgical year was experienced directly and intensely by the faithful, with fasting and abstinence being a striking way to mark seasons and fast days. Our contemporary era, with its rather minimal fasting and abstinence, is somewhat of an exception to most of church history.