The Assumption Fast dates back to ancient Christian times. In a sermon by Leo the Great, delivered around 450 AD, the Assumption Fast is clearly referred to. It says there: “The church fasts during the year are arranged in such a way that a special rule of abstinence is prescribed for each. Spring has a spring fast during Lent, summer – a summer fast after Pentecost (Peter’s fast), autumn – an autumn fast in the seventh month (the Assumption fast), and winter – a winter fast (Christmas fast).

Saint Simeon of Thessalonica writes that “…the fast during August (the Assumption fast) was introduced in honor of the Mother of the Word of God, Who, having learned in advance of Her repose, and since She always worked hard and fasted for us, although as holy and immaculate She had no need for fasting, began to pray especially fervently, preparing for the transition from this to the next life to meet Her Son, and our and her God Jesus Christ.

Therefore, we are also obliged to fast the Assumption or Great Assumption fast, Her supporting Her life, and beseeching Her to pray tirelessly for us. Some, however, say that this fast arose on the occasion of two feasts, namely the Transfiguration and the Assumption. I also consider it necessary to keep the memory of these two feasts, the first commemoration as a commemoration of the feast that gives us sanctification and the second as a commemoration of (the Virgin's) propitiation and intercession for us…”. The Assumption fast was finally established at the Council of Constantinople in 1166, presided over by Patriarch Luke. At that time it was confirmed that all Orthodox Christians, in accordance with ancient constitutions, should observe the fast of the Virgin from August 1-15 according to the church calendar. Theodore Valsamon writes about this council: "Some were in doubt about the length of the Assumption and Christmas fasts. On that occasion, the patriarch confirmed that, despite the fact that the days of these fasts are not indicated in writing anywhere, we are forced to follow the unwritten Church Tradition according to which we should fast from the first day of August and from the fourteenth day of November (according to the church calendar)."