Fasting, as we see it in the pages of the Bible, has been appropriated in the Christian tradition in a way that often abandons its biblical sense. In particular, it has become for many today a technique. What do I mean?
We make fasting a technique when we see it as something that intensifies our prayers and our pleas — like intensifying a color, when we think fasting — if properly practiced — will bring us special benefits (unique intimacy with God, answers to prayers), and when we think of it simply as a discipline to subdue the flesh and, if practiced properly, it will lead to moral purity. Pay attention to how often we speak of fasting and quickly slip into its benefits. In the Bible, fasting is never spoken of this way: those who fast sometimes have benefits. But, the Bible does not say fasting brought that benefit.

In each of the above fasting is a technique for an end. Treating fasting as a technique is not all that far from it being magic. We should get really nervous about this sort of framework, and whether we are aware of it or not, this unconscious sense that fasting is little more than a technique has led to its widespread disappearance among Protestants. Many of us believe that an external technique is of no use in and of itself.
As Christians we believe that what matters is the heart and our faith and our love — i.e., our relationship to God. We are justifiably skeptical about techniques bringing spirituality.
I do not believe the Bible teaches that fasting is a technique. (It does seem to me that 1 Cor 9:27 gets close, but fasting is not mentioned but neither do I want to deny that Paul believed we should be disciplined in our pursuit of love and holiness.)
By making fasting a technique, we shift fasting from anthropology (its biblical home) to spirituality. I’m not persuaded that fasting is a discipline so much as it is a potential environment for all the disciplines. (But that’s for later.) What I’m saying is this: fasting is what happens in the Bible when Israelites and Christians surrender the entire person — heart, soul, mind, spirit and body — to God. It is the inevitable bodily manifestation of a unified person offering herself or himself to God. (Thus, anthropology.) When we make it a technique, we shift it into spirituality. My claim is that the spiritual person in the Bible fasted; fasting did not make the person spiritual. The spiritual person’s prayers, etc, were answered — not because they fasted but because they laid themselves out before God totally and the body of a spiritual person fasted. A person feasting on God himself is not hungry for anything else. Fasting did not make the feast; the feast made the fasting.