Fasting is an important discipline, yet there is little teaching in scripture about the nature of fasting. We simply read that people did it. We know that fasting is abstaining from food for a period of time. We find most of the Bible's detailed teaching in the book of Isaiah. According to Isaiah, fasting is not for the purpose of having God hear us. It is not for us to humiliate ourselves before God, hoping He answers our prayers because of it. It is for the purpose of breaking the bands of wickedness and breaking yokes. It changes us because we put aside a need of the physical body and allow God to give us strength.
How its done, exactly, is not clear from scripture. One interesting verse in Acts says, "Then after fasting and praying they laid their hands on them and sent them off." One has to ask, how long were they together that after fasting and praying they sent them off?
It is good for ministers to teach some practical things. For example, if you decided to fast for five days, abstaining from food and only taking water, you need some wisdom about how to break that fast lest you do damage to your body.
A healthy lifestyle is also important. Many Christians are gluttons, and most Americans can identify with the temptation to eat too much as we have it available to us so readily due to the blessing of living here.