Great Lent is an Ascetic Fast:
by H.G. Bishop Serapion
The Church teaches us to fast until sunset. Fish is not allowed during this period. Also married couples should refrain from physical relations to give themselves time for fasting and prayer (1 Cor. 7: 5). We would like to emphasize the importance of the period of strict abstention during fasting. It is refraining from eating and drinking for a period of time, followed by eating vegetarian food.
Some people practice fasting by abstaining from meat and they eat vegetarian food, disregarding the period of strict abstention. These people should actually be regarded as vegetarians and not as fasting. A vegetarian eats only vegetarian food, but is not considered a fasting person. True fasting must be accompanied by abstention from food and drink until sunset as designated by the Church. However, due to variations in people’s physical and spiritual abilities, the Church gave the father of confession the authority to designate to his children the length of their strict abstinence. He determines what is suitable for their spiritual benefit according to the nature of their work, as well as their physical ability to endure fasting.