Is not this the kind of fasting I have chosen: to loose the chains of injustice and untie the cords of the yoke, to set the oppressed free and break every yoke? … Then your light will break forth like the dawn, and your healing will quickly appear; then your righteousness will go before you, and the glory of the Lord will be your rear guard. —Isaiah 58:6, 8
First, fasting must be secret (Matt. 6:16-18). When we are fasting we must not let the slightest hint of it leak out. Only God needs to know.
The second thing is that fasting must be special. I question if it ought to be done regularly. I don’t see fasting as something to be done whether you really need to or not, for example, making a commitment to fast every Friday. I think if it is used that way it will lose its significance.
Third, as we have seen, fasting must have a purpose. We must know what we want to achieve. It’s not like taking vitamins in the general hope that they will do us good.
The fourth point is that fasting must be sensible. Some people cannot fast for medical reasons. For example, if you are a diabetic, then that ought to disqualify you. And we must never fast without drinking plenty of liquids. There are various degrees of fasting. You can cut out one meal or two meals, or fast for a whole day or a number of days. However, anyone seeking to fast for more than two or three days should first seek the advice from an experienced Christian minister or counselor.
A fifth thing is that fasting must be spontaneous: that is, voluntary and from the heart. In my opinion, there could be danger in corporate fasting, for some may be acting reluctantly and under pressure.
The next thing I need to say is that fasting must be sacrificial. Isaiah 58 describes people who fasted but who loved it.
Finally, we must be quite clear about our motives, and we must have no mixed motives.
Fasting by itself is no magic answer to our problems. It is only effective when it symbolizes a deep longing for spiritual reality, and it demands a life of holiness and obedience to God. “Then,” says God in Isaiah 58:8, “shall thy light break forth as the morning, and thine health shall spring forth speedily” (KJV).
Excerpted from Worshipping God (Hodder & Stoughton, 2004).