What does the Bible teach about fasting?

We’re going to take a break this week from our discussion about identity and instead, due to the upcoming 30 Hour Famine this weekend, take a look at the topic of fasting. Depending on who you talk to you may get a different definition of what fasting is and what it isn’t. Some people would say that it has to be something that is done regularly. Some churches have universal days set aside where the whole church is asked to fast. But then on the other side, if you talk to some churches they’ll tell you that fasting is an outdated and unnecessary act that is legalistic. Some might even tell you that fasting is unhealthy and could lead to eating disorders. So which is correct?
We’re going to attempt to get a grasp on this question tonight and figure out what exactly is fasting? Is it required or commanded in the Bible? And then if we should fast, how do we go about it?
So let’s dive in a start out by looking at fasting within the Old Testament. The first mention in the Bible is in Judges 20:26. Israel is in the middle of a huge war with their fellow Jews and the tribe of Benjamin. A man’s concubine had been murdered by one of the villages of Benjamin and the nation of Israel wanted the men responsible to be handed over to be executed. Benjamin refused and responded by sending out their troops which at the time seemed a huge mistake since they would be putting their 26,000 troops against Israel’s 400,000.
For two days, Israel fought but instead of dominating Benjamin, they got their butts kicks and lost 40,000 men. Before going out on the third day is where we read verse 26. “Then all the Israelites went up to Bethel and wept in the presence of the Lord and fasted until evening. They also brought burnt offerings and peace offerings to the Lord.” Then on day three, instead of facing another beating, Israel killed all but 900 of Benjamin’s troops.
What role did fasting play for the people of Israel? Petition and prayer to God.
Was that why they won? I don’t know. Both verses 18 and 23 say that before day one and day two the people asked God for help and guidance. The asking does progress though from just a simple “ask” in verse 18, to weeping in verse 23 to the fasting in verse 26. And God’s answers progress as well. In verse 18 God says, “Judah should go first.” In verse 23 God says, “Go out and fight.” And in verse 28 God says, “Go! Tomorrow I will hand them over to you.” Does this mean that fasting will get an answer to prayers sooner than just regular prayers? Or more so, does it guarantee an answered prayer?
Let’s look at 2 Samuel 12:16-23 to look at this deeper. This passage comes at the end of the whole mess David got himself into with the woman named Bathsheba. He committed adultery with her, got her pregnant, tried to cover it up by having her husband come home from being at war and then ended up killing him since he wouldn’t have sex with his wife. When David was called out for his actions God said that one of the consequences would be that the baby would die. David, by fasting earnestly pleads that God would change his mind. No cigar!
Are there any differences/similarities worth mentioning between these two situations and what it teaches us about fasting? The similarity is that David uses it as a means of petition to God. The difference though is that the outcome does not match what David wanted. I think that in itself