What is fasting? The word fasting means to abstain from food and water for a certain time, and in the Bible we find that there were several men who did this act, and even Jesus himself told us about this, which is supposed to be the correct way in which we should fast.
Jesus said about fasting:
16 Moreover when ye fast, be not, as the hypocrites, of a sad countenance: for they disfigure their faces, that they may appear unto men to fast. Verily I say unto you, They have their reward.
17 But thou, when thou fastest, anoint thine head, and wash thy face;
18 That thou appear not unto men to fast, but unto thy Father which is in secret: and thy Father, which seeth in secret, shall reward thee openly.