The Christian fast is a period of time during which one forgoes food and, instead, uses mealtime to pray.
The traditional purpose of the fast has been to ask God to intervene in our lives in a miraculous way. We have learned, however, that God encourages His children to fast so that they may grow more like Jesus, grow closer to God, and demonstrate love for the less fortunate.
A great deal of Internet space is used up explaining whether to totally abstain from food, whether or not to drink juice or water during a fast, and whether abstaining from other things counts as a fast.
Here’s my answer to that: it’s between you and God. The Bible mentions abstaining from sex for the sake of growing close to God. If you wish to abstain from other things, ask God.
When you fast, do so privately. When you pray, do so privately. Fasting and prayer is designed to nurture your relationship with God, not your standing in the church. Seek to be like Jesus.