Why do people fast or refrain from eating meat during Lent?
Lent has become a time for penitence and self-examination, study, and spiritual discipline. Perhaps the discipline most commonly associated with Lent is fasting, which can take many forms, such as giving up entire meals, or certain foods (like meat), or radically changing a diet, in order to be made mindful of one's humanity and of God's providence. One tradition was to stop using leavening during Lent. Hence on the day before Ash Wednesday, Christians observed “Fat Tuesday,” or Shrove Tuesday, or Mardi Gras, when the household would enjoy its last use of leavening until Easter Day. One form of fasting in Lent (or at other times) is to refrain from eating meat. Hence the serving of fish as a non-meat meal. The point is self-denial. Those who eat fish all the time and rarely eat meat might want to undertake a different fast.