Why can't you eat meat on Fridays during Lent?

The practice of abstinence (doing without certain things) goes back to the Old Testament and the Jewish dietary laws which were carried over into parts of the early Christian church until the Council of Jerusalem (Acts 15). The theological reasoning is that it is a method of atoning for sin since chastising the body brings it under control of the spirit. Abstinence is first mentioned in a Church document in a decree of the Council of Toledo in the year A.D. 447 where the custom was to abstain primarily from meat on all Fridays and on days of penance. Canon 1251 of the 1983 Code of Canon Law prescribes "abstinence from meat, or from some other food as decided upon by the Episcopal Conference (conference of bishops) on all Fridays, unless a solemnity should fall on a Friday. Abstinence and fasting are to be observed on Ash Wednesday and Good Friday." The National Conference of Catholic Bishops of the United States made abstinence from meat mandatory on Ash Wednesday and all Fridays of Lent and recommended that it be observed on all Fridays of the year but has allowed individual Catholics to substitute another penance on Fridays if they could not abstain from meat. For purposes of abstinence, fish is not considered to be meat because it comes from a cold-blooded animal rather than a warm-blooded one. Secondarily, early Christian art and literature used fish as a symbol of the Eucharist because the Greek word for fish, ichthus, is an acrostic (the first letters form the word) for "Jesus Christ, Son of God, Savior."

The 40 days of Lent (Sundays are excluded from the count since we celebrate the resurrection of the Lord on this day) signify the change which we wish to make in our life. Throughout Holy Scripture, the number 40 signifies a time of change. During this time abstinence from something, whether it be sweets, coffee or TV is an offering to God and a method of prayer. Every time we are tempted by whatever we have decided to abstain from, we are to remind ourselves that we have given this up for God so that He can bring us closer to Him.