People complained to Jesus saying, “Why do the disciples of John fast often, and make prayers, and likewise the disciples of the Pharisees; but yours go on eating and drinking” (Luke 5:33). But Jesus replied that as long as he is with them his disciples should not fast, but after he is taken away then “they will fast in those days” (Luke 5:35). This is why Jesus also gave them instructions on how to fast (Matthew 6:16-18). If they were never to fast, such instructions would be pointless.
Biblical accounts vividly portray that the disciples were fasting after the departure of Jesus. Fasting and prayer became a daily routine. In the course of their prayer and fasting in Acts 13:3, the Spirit of God through prophecy called out Paul and Barnabas for the assigned missionary work.
Paul, in 2 Corinthians 6:3-5 admonished Christian workers not to receive the grace of God in vain. Rather, giving no offence in anything, that the ministry be not blamed, but in all things approving ourselves as the ministers of God, in much patience, in afflictions, in necessities, in distresses, in stripes, in imprisonments, in tumults, in labours, in watching and in fastings.
Fasting is a Christian discipline which must be undertaken with all seriousness. Besides, it has several positive medically proven results which enable the human body to remain healthy.