The penitential and preparatory season of Lent includes 40 days of fasting, but if you look at the calendar closely enough and do the math you’ll see that the actual season is a bit longer. Why? Because within those 40 days are excluded each and every Sunday. Sundays are feast days and cannot be fast days. It is for this reason that Sundays are labeled as “Sundays in Lent” rather than “Sundays of Lent.”
Why are Sundays excluded from the Lenten fast? Or, put more positively and more theologically descriptive, what is the difference between fasting and feasting?
The Church calendar is comprised of an ongoing series of feasts and fasts. Saints are given feast days, as are important biblical events (Transfiguration, Annunciation, etc.) while other days and seasons are reserved for fasting (Fridays, Advent, Lent, etc.). Easter is considered to be the “Feast of Feasts” and every Sunday throughout the year is a celebration and commemoration of the Paschal feast.
Our Lord said in Mark 2:19, “How can the [wedding] guests fast when celebrating with the Groom?” The point being that weddings are times of celebration and joy not reserved for fasting or penitence. If Christ is the groom and the Church His bride, and if Sunday is the Lord’s Day, then how could we possibly do anything but feast?
Within the early church, and still maintained throughout modern Christian theology, was the concept that Sunday was the first day, the third day, and the eighth day. I have written about this unique thought elsewhere:
Sunday is the first day of the week and the first day of creation. It is the day of the Sun of Righteousness, given that Saturday is the Sabbath, the day of rest. It is the third day, because it was on Sunday that our Lord was raised from the grave, having conquered sin, death, and the devil; having “trampled down death by death,” he was raised to new life, echoing his bold claim from earlier in John’s gospel, “I am the resurrection and the life.” Finally, Sunday is the eighth day because the resurrection changes everything: it is the first day of the new week, the first day of the new creation. It is the breaking in of God’s Kingdom in the here and now. John marks his Gospel according to days, and the Sunday of the resurrection is both a continuation of the first day but also its fulfillment.
It is this very combination of metaphors, meaning, and symbolism that creates our annual celebration of Easter and our 51 mini-celebrations every other Sunday. Easter is always the referent on Sunday and as has already been pointed out, fasting cannot take place on the Feast of Feasts.
The Orthodox celebrate the Eucharist during the weekdays of Lent using “pre-Sanctified gifts.” Such an action is evidence of maintaining the balance between feasting and fasting. Fr. Alexander Schmemann wrote:
“As the sacrament and the celebration of the Kingdom, as the feast of the Church, it is incompatible with fast and is not celebrated during Lent; as the grace and the power of the Kingdom which are at work in the world, as our supplier of the ‘essential food’ and the weapon of our spiritual fight, it is at the very center of the fast, it is indeed the heavenly manna that keeps us alive on our journey through the desert of Lent.” – Schmemann, Great Lent, 48-49
This leaves us with two basic questions: first, what does a Lenten fast look like? And second, how do we make sense of the tension between fasting and feasting.
Fr. Schmemann highlights two different types of fasts when he writes of an ascetical fast and a complete or total fast. I’d like to briefly unpack both of these fasts in the hopes that they will help in your observation of Lent.
There are indeed two ways or modes of fasting rooted both in Scripture and Tradition, and which correspond to two distinct needs or states of man. The first one can be termed total fast for it consists of total abstinence from food and drink. One can define the second one as ascetical fast for it consists mainly in abstinence from certain foods and in substantial reduction of the dietary regimen… – Schmemann, Great Lent, 49.
With regard to tension, I am firmly convinced that the whole of our Christian lives is an ongoing ebb-and-flow of fasting and feasting. We fast in penitence, preparation, joy, and anticipation. The Christian year gives us the two seasons of Advent and Lent as prime times for intentional fasting. It is also common to fast on Fridays—in honor of our Lord’s sacrifice on Good Friday—as well.
Lent is about self-denial, repentance, and seeking the Lord. The fasting days of Lent are designed for individuals to deny themselves of God’s gifts in order to focus more fully on God. This could include meat, dairy, and alcohol. But fasting is always done with the Feast of Feasts in view and never to earn or merit our participation at the Altar. Fasting is about preparing for Feasting. As we prepare to celebrate Christ’s resurrection and his second Advent, may we deny ourselves daily and fasting in order to find him.
 Emphasis mine