Fast it's the state of the one who doesn'tfeeds from the day before. It's a situation of partial or total abstinence fromfoods, in a certain period of time. To be fasting is to be without eating any food for long hours. Fasting is practicing fasting.
Fasting is a practice widely used by several religions, which consists of abstinence from food, which can be total, where during a certain period, the follower abstains from any food, or a partial fast, where on certain days a specific type of food is avoided, to fulfill a ritual of penance.
For the Catholic religion, Good Friday is the day when the faithful must make the sacrifice of fasting, and not eat meat. For religion, fasting is a way to abstain from the pleasure of red meat and seek in prayers the sharing of Christ's suffering, passed on the cross.
For Jews, the Day of Atonement, one of the most important dates in Judaism, is celebrated with the practice of total fasting and religious celebrations. Fasting is observed from sunset one day to sunset the next day.
Muslims fast from dawn to sunset on the festive days of Ramadan so that all their sins are forgiven. It is considered a time of faith renewal.
In a figurative sense, fasting is going through deprivation or abstention from something.