Fasting usually means abstaining from something, usually food, for a spiritual reason. It is an often, overlooked spiritual discipline, but Jesus spoke about it in the Sermon on the Mount and made it equal with financial giving and prayer (Matthew 6). Maybe it is something we should look into.
The Bible talks a lot about fasting because a lot of godly people fasted. Here is a taste (pardon the pun) of some fasters: Moses (Exodus 34:28; Deut. 9:9,18), David (2 Samuel 12:16), Nehemiah (Nehemiah 1:4); Esther (Esther 4:16), Anna (Luke 2:37), Paul (Acts 14:23), Jesus (Matthew 4:1-2), and the early church (Acts 13:2).
The purpose of fasting was usually to re-center the person’s heart and mind and devotion on God. It wasn’t primarily a physical health thing but a spiritual health thing. In an interesting psychological way, feeling deprived physically aids our desire to be satisfied spiritually. God honors this practice.
For me, it does at least three things.