Since Vatican II in 1965, the Catholic Church has become significantly more lax on its insistence that certain guidelines are followed, but one of them that is still fairly ridgedly observed is the tradition of not eating meat during Lent.
The ancient Church gave up meat every Friday. The reasoning was simple: as a Mediterranean based religion, fish was a cheap meal that most people could afford. Beef, lamb, or pork was significantly more expensive and only available to the wealthier of ancient societies. In order to share a "common meal" and strengthen the bonds that tied all Christians, everyone would opt for fish (or no expensive meats) on Fridays.
With Vatican II, the council acknowledged that fish was no longer a poor man's food. It was instead a more expensive meal than other meats. Don't be fooled - the regulation of not eating meat on Fridays (and that means
all Fridays) is still present in the Catechism. However, Vatican II added the provision that one is allowed to substitute another penance for the giving up of meat. Most Catholics forget the other penance and eat meat anyway, which has led to the belief that giving up meat during Lent is the only time that it has to be done.
The giving up of meat should be more strictly adhered to during Lent, which is a more somber and reflective time.
For a little bit more on Lent, you can see my most recent opinion column:
http://www.kstatecollegian.com/article.php?a=4814 .
