Lent refers to the 40-day period starting on Ash Wednesday, ending on Holy Saturday (the day before Easter Sunday) but excluding all Sundays in between. While Lent is often ignored entirely by the Protestant community and given only token observance by Roman Catholics, among the Orthodox and many Eastern sects it remains a strictly observed fast much like the Muslim Ramadan.

The teaching of the Holy Father may be simply paraphrased: the obligation to do penance is a serious one; the obligation to observe, as a whole or "substantially", the penitential days specified by the Church is also serious. No one should be scrupulous in this regard; failure to observe individual days of penance is not considered serious; rather it is the failure to observe a substantial number of penitential days which must be considered serious. People should seek to do more rather than less.
The historical basis for the Lenten fast is Jesus's 40-day fast before beginning his ministry. It is also a time of reflection and penitence before the feast of the Resurrection, after which fasting is in fact prohibited! However, the New Testament does not lay out any specific dates or rules for fasting, and the idea of fasting seems to be largely copied from Jewish or even Roman tradition. (This is the main reason why most Protestant churches reject the tradition of the fast.) Most Christian teaching on the fast takes pains to point out that fasting in itself is not a virtue, it is only a means for self-control and more frequent prayer.

The first main component of Lent is the Obligation of Abstinence, which applies to all older than 14. For Roman Catholics, this has been interpreted to mean abstinence from eating flesh meat in any form (including broth), but not including fish. Nearly all Roman Catholic churches observe the Obligation on Ash Wednesday and Good Friday; most extend it to all other Fridays during Lent as well, but only a few require abstinence throughout the entire 40-day period. There is even a concept of "partial abstinence", meaning eating meat only once per day.

Instead of fasting, some Roman Catholics choose to abstain from a different vice: popular choices are coffee, chocolate, alcohol and even tobacco (not a minor undertaking!).

For the Orthodox, the rules of abstinence are much more complex. Basically, there are four categories of food to abstain from:

  1. Meat and Meat Products (includes beef, pork, chicken, etc., as well as items which have beef gelatin, lard, etc)
  2. Dairy Products (includes butter, eggs, milk, cheese, etc., as well as items containing dairy whey, milk extracts, etc.)
  3. Fish (includes sardines, tuna, bass, trout, shark, pike, etc. but not shell fish such as lobster, shrimp, crab, oysters, scallops, clams, mussels, etc.)
  4. Olive Oil (according to some, this would extend to all oil) and Wine (which includes all alcoholic beverages such as whiskey, beer, etc.)
Left out are grains, vegetables, fruits and -- oddly enough -- shellfish.

Which of the restricted groups can be eaten depends on the day and the strictness of one's observance. The strictest form is the following:

  • Weekdays during Lent: Abstinence of categories 1 through 4
  • Saturdays and Sundays during Lent: Abstinence of categories 1 through 3
  • Feast of the Annunciation and Palm Sunday: Abstinence of categories 1 and 2
Even among the Orthodox, many limit their observance to not eating meat on Fridays (and sometimes Wednesdays).

Being a little hungry during the day becomes a constant reminder of God, of our dependence on Him, and of the fact that the Lord alone can give us "food that lasts for eternal life" (John 6:27).
The second component is the Law of Fasting, also known as the Law of Strict Abstinence. According to the Roman Catholic church, fasting must be observed on Ash Wednesday and Good Friday, and it is "encouraged" for Holy Saturday, for all who are older than 18 but younger than 59 years. Fasting takes the form of eating only one full meal per day, although two additional small meals are permitted "if necessary". Eating food between meals is forbidden.

The Orthodox observe the Law of Fasting during all weekdays of Lent, but less strictly: the only admonition is to eat less than usual and avoid eating between meals. Of course, many faithful (especially monks) fast more strictly, some practicing xerophagia (consuming only bread and water) or eating nothing at all during the day. St. John Chrysostom extends the definition of fasting to strict abstention from all evil.

While Lent itself is often forgotten, there are many reminders of the festivities surrounding the fast in this secular world of ours. The day before Ash Wednesday and the start of the fast is Shrove Tuesday (aka Mardi Gras or Fat Tuesday), originally a day to fatten up before the fast but now an occasion for much drunken revelry. In Finland, custom demands that on Shrove Tuesday (laskijaistiistai) everybody eat pea soup, eat sugary buns and go sledding. And Easter Sunday at the end of the fast is celebrated with pastel-colored Easter bunnies passing out candy and painted eggs, which I'm sure is exactly what the Desert Fathers had in mind...