Scripture does not command Christians to fast. It is not something that God requires or demands of Christians. At the same time, the Bible presents fasting as something that is good, profitable, and expected. The Book of Acts records believers fasting before they made important decisions (Acts 13:4; 14:23). Fasting and prayer are often linked together (Luke 2:37; 5:33). Too often, the focus of fasting is on the lack of food. Instead, the purpose of fasting should be to take your eyes off the things of this world, and instead focus on God. Fasting is a way to demonstrate to God, and to yourself, that you are serious about your relationship with Him. Fasting helps you to gain a new perspective and a renewed reliance upon God.

Although fasting in Scripture is almost always a fasting from food, there are other ways to fast. Anything you can temporarily give up in order to better focus on God can be considered a fast (1 Corinthians 7:1-5). Fasting should be limited to a set time, especially when the fasting is from food. Extended periods of time without eating are harmful to the body. Fasting is not intended to punish your flesh, but to focus on God. Fasting should not be considered a “dieting method” either. Do not fast to lose weight, but rather to gain deeper fellowship with God. Yes, anyone can fast. Some may not be able to fast from food (diabetics for example), but everyone can temporarily give up something in order to focus on God.

By taking our eyes off the things of this world, we can focus better on Christ. Fasting is not a way to get God to do what we want. Fasting changes us, not God. Fasting is not a way to appear more spiritual than others. Fasting is to be done in a spirit of humility and a joyful attitude. Matthew 6:16-18 declares, “When you fast, do not look somber as the hypocrites do, for they disfigure their faces to show men they are fasting. I tell you the truth, they have received their reward in full. But when you fast, put oil on your head and wash your face, so that it will not be obvious to men that you are fasting, but only to your Father, who is unseen; and your Father, who sees what is done in secret, will reward you.”

cited from http://www.gotquestions.org/fasting-Christian.html

religion is a confusing misress indeed!

sources: fickle