Fasting is an important part of the Eastern Orthodox religious tradition. Devout Orthodox Christians observe many fasts throughout the year.
One of these fasts occurs during the Christmas season. It is called the Nativity Fast (or Philip’s Fast or the Philippian Fast, since the fast period starts the day after the November 14 Feast of St. Philip the Apostle).
There are differences from nation to nation and from Orthodox church to church on the details of how the Nativity Fast is to be observed, but a general overview can be given that will fit most jurisdictions fairly well.
As noted, the Nativity Fast generally starts on November 15, though some churches observe a shorter fast beginning December 10. (Note that dates are according to the Julian calendar used in the Orthodox faith. Add 13 days to convert to the standard Gregorian calendar. So for instance the fast starts on November 28 according to the Gregorian calendar.)
There are different stages to the fast, with different restrictions. The first period is from November 15 through December 19. No meat (including poultry, eggs, and all meat products) and no dairy are allowed. Wine and oil are allowed on Tuesdays, Thursdays, Saturdays, and Sundays, and disallowed on Mondays, Wednesdays, and Fridays. Fish is allowed on Saturdays and Sundays, and disallowed the other five days.
The second period is from December 20 through December 24, and here the fast is more strict. No meat, no dairy, and no fish are allowed. Wine and oil are allowed on Saturday and Sunday (if there happens to be a Saturday and/or Sunday during that five day stretch), and disallowed otherwise. If the 24th falls on a day other than Saturday or Sunday, no solid food at all is to be consumed until the first star is seen in the evening sky.
The third period is from December 25 through January 4. For these eleven days, the dietary restrictions are lifted, even the ones that otherwise apply during non-fast periods in the Orthodox religion, such as the avoidance of meat and fish on Wednesdays and Fridays.
Finally, January 5-the eve of Epiphany-returns to a strict fast day with the same rules as December 20 through December 24.
The very young, the elderly, nursing mothers, and people who are ill are not obligated to observe Orthodox fasts, including the Nativity Fast. Other exemptions may be permitted on an individual basis in consultation with one’s spiritual confessor.
The purpose of fasting is to foster self-discipline and to deny oneself certain worldly pleasures with an attitude of humility and repentance. In order for the fast to be most effective, it must not be limited to matters involving food or even just the physical body in general. A period of fasting is also meant to be a time when one is more conscious than ever of refraining from anger, covetousness, and greed, and when one shifts one’s attention to godly pursuits such as giving alms to the poor.
“The Christmas Fast.” Pravoslavie.ru.
“Guidelines for the Nativity Fast.” Antiochian Orthodox Christian Archdiocese.