The law of fasting refers to “those who have attained their majority,” which may differ from culture to culture and country to country. In the United States, the U.S. Conference of Catholic Bishops (USCCB) has declared the age of fasting is from the completion of the 18th year to the beginning of the 60th.
The USCCB also allows the substitution of some form of penance for abstinence on all Fridays of the year, except for the Fridays of Lent. The rules for fasting and abstinence in the United States are:
à Every person 14 years of age or older must abstain from meat (and items made with meat) on Ash Wednesday, Good Friday, and every Friday of Lent.
à Every person between the ages of 18 and 59 (your 18th birthday completes your 18th year, and your 59th birthday begins your 60th year) must fast on Ash Wednesday and Good Friday. Fasting consists of one full meal per day, with two smaller meals that do not add up to a full meal, and no snacks.
Every person 14 years of age or older must abstain from meat on all other Fridays of the year unless he or she substitutes some other form of penance for abstinence.