The rules for fasting and abstinence in the Catholic Church are set forth in the Code of Canon Law (for the Roman Catholic Church) and in the Code of Canons of Oriental Churches (for the Eastern Catholic Churches). To a limited extent, they can be modified by the conference of bishops for each particular country (or, in the Eastern Churches, for each particular rite).
The Code of Canon Law prescribes (Canons 1250-1252):
Can. 1250: The penitential days and times in the universal Church are every Friday of the whole year and the season of Lent.
Can. 1251: Abstinence from meat, or from some other food as determined by the Episcopal Conference, is to be observed on all Fridays, unless a solemnity should fall on a Friday. Abstinence and fasting are to be observed on Ash Wednesday and Good Friday.
Can. 1252: The law of abstinence binds those who have completed their fourteenth year. The law of fasting binds those who have attained their majority, until the beginning of their sixtieth year. Pastors of souls and parents are to ensure that even those who by reason of their age are not bound by the law of fasting and abstinence, are taught the true meaning of penance.
In the United States, the U.S. Conference of Catholic Bishops has declared that "the age of fasting is from the completion of the eighteenth year to the beginning of the sixtieth." The USCCB also allows the substitution of some other form of penance for abstinence on all of the Fridays of the year, except for those Fridays in Lent. Thus, the rules for fasting and abstinence in the United States are:
- Every person 14 years of age or older must abstain from meat (and items made with meat) on Ash Wednesday, Good Friday, and all the Fridays of Lent.
- Every person between the age of 18 and 60 must fast on Ash Wednesday and Good Friday.
- Every person 14 years of age or older must abstain from meat (and items made with meat) on all other Fridays of the year, unless he or she substitutes some other form of penance for abstinence.
If you are outside the United States, you should check with the bishops' conference for your country.
For the Eastern Catholic Churches, the Code of Canons of Oriental Churches prescribes (Canon 882):
Can. 882: On the days of penance the Christian faithful are obliged to observe fast or abstinence in the manner established by the particular law of their Church sui iuris.
Thus, Eastern Catholics should check with the governing body for their particular rite.