I just led a Bible study on this topic Sunday night so I figured I'd share my thoughts about fasting while all the passages of note are still fresh on my mind.
In the Old Testament, there are approximately 25 passages on the topic of fasting. The vast majority of these cases, though, are EXAMPLES of fasting, not TEACHING about fasting. The 'details' of these examples varied. Fasting was done individually and corporately. Fasting was done by Israelites and non-Israelites. Fasting was done for as little as 1 meal or as long as 40 days. Fasting could be done regularly or spontaneously. Fasting could be done as part of repentance for apostacy, after losing a loved one, or before a big battle, etc. Fasting was often accompanied with other important attitudes/disciplines
(repentance, mourning, humility, chastity, faith, prayer, confession, etc).
The New Testament doesn't say a ton about fasting, but Jesus did speak on the issue directly in a couple of spots. Jesus assumed His listeners would fast, though He never clearly commanded it. He seems to have implied fasting was necessary for certain spiritual victories. The early church, from Jesus disciples through the 1st centuries, seem to have included fasting as a regular spiritual discipline. Jesus fasted before His ministry. The people were fasting when Paul and Barnabas were called toward the 1st missionary journey, etc. The early church recommended fasting on Wednesdays & Friday's, usually until 3pm (though it could be extended), but rebuked anyone who fasted on the Lord's Day (Sunday).
There are many benefits to fasting. It provides you with bonus TIME. Instead of spending time preparing and eating a meal, fasting allows you to spend that time more directly in God's presence. It provides you with bonus RESOURCES. Instead of spending money on food, you can give that money (or food) to someone in need. Fasting humbles us, reminding us of the frailty of the flesh. Fasting empowers us by connecting us with the source of our power, God Himself.
I really recommend that all Christians try a fast. Not in a legalistic way, but as a voluntary spiritual discipline as they feel led by the Spirit. Try a private fast. See if you can take part in a corporate fast. Use the time and resources that you free up for the Lord's work.