In 1966, Pope Paul VI promulgated a new set of regulations for fasting and abstaining by his apostolic constitution, Paenitemini. These new rules are listed in the 1983 Code of Canon Law, Canons 1249-1253 and all Roman Catholics today are bound to strictly observe them.
The overview below sums it up well:
Lastly, fasting during all weekdays in Lent is still “strongly recommended” by the National Conference of Catholic Bishops.
In Paenitemini, Pope Paul VI gave authority to the episcopal conferences on how the universal rules would be applied in their region. On November 18, 1966, the National Conference of Catholic Bishops legislated the following to be observed in the United States:
- Abstinence is obligatory on all Fridays of Lent, except Solemnities (i.e., I Class Feasts).
- Fasting and abstinence are obligatory on Ash Wednesday and Good Friday.
- Abstinence on all Fridays, though not obligatory under pain of sin, is “especially recommended.”
- Fasting on all weekdays of Lent, though not obligatory under pain of sin, is “strongly recommended.”
Thus the Church still encourages the Lenten fast requirements found in the 1917 Code but does not do so under any obligation of sin to the faithful.
I wholeheartedly recommend readers access the Live The Fast website, which promotes fasting, particularly on Wednesdays and Fridays throughout the year. The site provides great information on current minimum fasting requirements and basically taught me the majority of what I know with respect to fasting today. It is a great site!