In the East, Wednesdays and Fridays have an equal fast - Wednesday commemorates the beginning of our Lord’s Passion, the betrayal of Judas when he went to the leaders, and Friday the culmination of our Lord’s Passion.
'St. Benedict (Canon 41) also designates that the fast of Wednesday and Friday is until the ninth hour. And Balsamon forbids the consumption of shellfish on Wednesday and Friday just as during Great Lent. Let us therefore stop insensibly thinking that the fast of Wednesday and Friday is not an Apostolic directive, for behold, the Apostles in their Canons number this fast together with that of Great Lent, and in the Apostolic Constitutions they number it together with the fast of Holy Week, saying:
“One must fast during Holy Week and Wednesday and Friday.”[18] But why should I say that this regulation is only of the Apostles? It is a regulation of Christ Himself, for this is what the Apostles say in Book V, ch. 14 of the Constitutions:
“He (that is, Christ) commanded us to fast on Wednesday and Friday.”[19] We therefore fast on these days according to the Holy Hieromartyr Peter (Canon 15): “On Wednesday because on this day the council of the Jews was gathered to betray our Lord; on Friday because on this day He suffered death for our salvation.” The divine Jerome says the same thing.
Therefore, because the fast of Great Lent is equal to the fast of Wednesday and Friday it follows that, for those who are sick or weak, the relaxation of the fast is also to be equal during these fasts. For this reason, as Canons 8 and 10 of Timothy allow a woman who is pregnant during the Great Fast to consume as much wine and food as is necessary for her condition, this also applies to the fast of Wednesday and Friday. The same holds for those who have become weak from excessive sickness, that is, they are allowed to consume oil and wine during these fasting periods. So says the divine Jerome: “The fast of Wednesday and Friday is not to be broken unless there is great necessity.” The divine Augustine says the same.[20]"
Alex