All Roman Catholics, whether celebrating the Ordinary or Extraordinary Form, follow the same laws of fasting and abstinence.
In 1966 Pope Paul VI reorganized the Church's practice of public penance in his "Apostolic Constitution on Penance" (Poenitemini). The 1983 revision of the Code of Canon Law incorporated the changes made by Pope Paul. Not long after that, the U.S. bishops applied the canonical requirements to the practice of public penance in our country.
To sum up those requirements, Catholics between the ages of 18 and 59 are obliged to fast on Ash Wednesday and Good Friday. In addition, all Catholics 14 years old and older must abstain from meat on Ash Wednesday, Good Friday and all the Fridays of Lent.
Fasting as explained by the U.S. bishops means partaking of only one full meal. Some food (not equaling another full meal) is permitted at breakfast and around midday or in the evening—depending on when a person chooses to eat the main or full meal.
Abstinence forbids the use of meat, but not of eggs, milk products or condiments made of animal fat.
Catholics who attend the Traditional Latin Mass often wish to maintain the former disciplines of fasting and abstinence on a voluntary basis. The priests and brothers of the Canons Regular of St. John Cantius maintain abstinence from meat on Wednesdays and Fridays during the year, and abstain, additionally, from dairy products during the Lenten season.