By Dr. John Fountoulis
Why in times of fasting do we fast from oil and fish but not from olives and fish roe?
The old and true fast consists of total abstinence of food or xerophagia [only eating dry foods]. Since this cannot be maintained during long periods of fasting in the ecclesiastical year because of difficult living conditions or lack of zeal, several accommodations have been designed for the application of fasting by all believers.
In ancient times Christians after the ninth hour (3:00 pm) on Lenten days partook only of water and bread. Gradually, however, not only was the duration of complete abstinence from food limited to normal time, and on other days Lenten Vespers and the Presanctified Liturgy were moved to the morning because of this, but other types of food were used, such as fruits, legumes, crustaceans, mollusks, etc.
Within this context it can be understood why we eat olives on days you do not eat oil, and fish roe on days we abstain from fish. For the former we can invoke the fact that olives are eaten as fruit, while the ban on oil is on foods prepared with oil. For the latter justification is less reasonable, since the same is not allowed for milk or eggs, but they are prohibited in our fasts as "fruit and produce of animals" in the 56th Canon of the Quinisext Ecumenical Synod. I know, however, devout Christians who understand this as "oikonomia", and on the days of great fasts and the night before Holy Communion they abstain from olives and fish roe.
It is true that we often hear this question from well-meaning believers and more than a few who view the fasts as an irony. In both cases we emphasize the flexibility and philanthropy of the customs and rules of the Church, which do not have a purpose to exterminate people but to help them to exercise restraint and dominate the passions. If these foods scandalize them, they can abstain from them without being in "contempt" or "judgement" against the Church for its benevolence, according to the Apostle (Romans 14:3). For the Church to struggle for the liquidation of relevant fasting customs and foods to be eaten or not is not necessary nor is it able to stay within the bounds of seriousness. What is primarily needed is to fast for the spiritual benefit that comes from this, and attempt as far as possible for the faithful to be in compliance with the relevant provisions of the Church, which have severely died down today.
Source: Translated by John Sanidopoulos