It is believed that, although it lasts 40 days, the Christ's Nativity fast is not as strict as the long period of fasting preceding Easter and the feast of the Assumption of the Theotokos.

The long period of abstinence from food of animal origin is preceded by the consumption of meat products on November 14 and mutual forgiveness, which calms the mind and prepares the faithful for the long period of spiritual purification and bodily deprivation, in which leading should be the words of St. John Chrysostom: "The benefit of fasting should not limit you only to abstinence from eating food, because true fasting is distancing yourself from evils. Avoid injustice. Forgive your neighbor's offense. Forgive your debtors".‎

According to the Statute of the Bulgarian Orthodox Church, during the first week of the Christmas fast, as well as from December 20 to 24 inclusive, only vegetable food with vegetable oil is consumed. During the rest of the fasting days (excluding Wednesdays and Fridays), invertebrates (snails, clams, octopuses, etc.) are allowed. 

Tradition dictates that on November 21 - the feast of the Introduction of the Virgin into the Temple, and on December 6 - Saint Nicholas Day, fish can also be consumed.