The Dormition fast was established as preceding the great feast of the Dormition of the Mother of God. It lasts two weeks starting from August 1/14 till August 14/27 (Gregorian Calendar/Julian Calendar).
The Dormition fast is not as strict as Lent, but it is stricter than the Apostle’s and Nativity fasts.
The spiritual fast is closely united with the bodily, just as our soul is united with the body, penetrates it, enlivens it, and makes one united whole with it, as the soul and body make one living human being. Therefore, in fasting bodily we must at the same time fast spiritually: “Brothers, in fasting bodily let us also fast spiritually, severing all union with unrighteousness,” the Holy Church enjoins us.
The main thing in fasting bodily is restraint from abundant, tasty and sweet foods; the main thing in fasting spiritually is restraint from passionate, sinful movements that indulge our sensual inclinations and vices. The former is renunciation of the more nourishing foods for fasting food, which is less nourishing; the latter is the renunciation of our favorite sins for exercise in the virtues which oppose them.
The essence of the fast is expressed in the following Church hymn: “If you fast from food, my soul, but are not purified of the passions, in vain do we comfort ourselves by not eating. For if the fast does not bring correction, then it will be hateful to God as false, and you will be like unto the evil demons, who never eat.”