Q — Canon Law says that Catholics should abstain from meat on all Fridays. Other Catholic textbooks say only the Fridays of Lent. Explain.

A — The Code of Canon Law, canons 1249-1253 govern the days of penance for Catholics. The opening sentence in canon 1253 reads as follows: “The Episcopal Conference can determine more particular ways in which fasting and abstinence are to be observed…” That particular sentence helps to clear up some of the possible confusion. The canonical tradition maintains that Catholics who have completed their 14th year ought to abstain from meat and meat products on all Fridays of the year until they have begun their 60th year. In our country, the United States Conference of Catholic Bishops has determined that this rule should obtain from the completion of the 18th year until the beginning of the 60th year. The United States Conference of Catholic Bishops has also permitted substituting some form of penance other than abstention from meat on the normal Fridays of the year. The only exception is the Fridays of Lent, and on those Fridays abstention from meat remains the norm for the ages indicated above.

Q —Why does the Catholic Church keep Sunday as a day of worship instead of the Sabbath of the Bible?
A — The shortest response to this question comes from the church’s “General Norms for the Liturgical Year and the Calendar”: The Church celebrates the paschal mystery on the first day of the week, known as the Lord’s Day or Sunday.  This follows a tradition handed down from the apostles and having its origin from the day of Christ’s resurrection.  Thus Sunday must be ranked as the first holy day of all (par. 4).
The Resurrection of the Lord occurred “on the first day of the week.” This is one detail in respect of the Resurrection narratives on which all the evangelists agree, even when they differ on other details: see Mark 16.2; Matthew 28.1; Luke 24.1; John 20.1. This is the most basic reason behind worship on Sunday. And so, from the earliest times, Christians assembled on the first day of the week.  
While there is no explicit command to worship on the first day of the week, worship on the first day seems to be presupposed: Acts 20.6-11; 1 Cor. 16.2. Thus, Sunday becomes, as it were, a mini-Easter, celebrating life in the Risen Lord.