Should Christians fast?

Should Christians fast?
Fasting is the practice of going without something, usually food, for the purpose of focusing on God.  There are plenty of examples of fasting in the Bible to show that people in various situations decided to fast.
There is no commandment in scripture concerning when or how often a person should fast.  God doesn't demand that Christians fast but rather presents it as a voluntary and beneficial activity.  Some examples include
Acts 13:3  Then after fasting and praying they laid their hands on them and sent them off. 
Acts 14:23  And when they had appointed elders for them in every church, with prayer and fasting they committed them to the Lord in whom they had believed.
Luk 2:37  and then as a widow until she was eighty-four. She did not depart from the temple, worshiping with fasting and prayer night and day. 
Luke 5:33  And they said to him, "The disciples of John fast often and offer prayers, and so do the disciples of the Pharisees, but yours eat and drink."
During the second forty days on Sinai, Moses fasted. "I did neither eat bread nor drink water, because of all your sins" (Deuteronomy 9:18). "I fell down before the Lord... because He said He would destroy you" (verse 25). Because the people sinned, he fasted and interceded. 
Israel defeated by Benjamin (Judges 20:26), Jehoshaphat meeting a vast army (2 Chronicles 20:3) and Esther facing death (Esther 4:15) all fasted. Even the unsaved of Nineveh, on hearing Jonah preach, "believe God, and proclaimed a fast" (Jonah 3:5). The practice was not limited to the law nor to Israel.
While food may be the most common form of fasting, any activity that we choose to ignore in order to devote more attention to God could be considered a fast.
The purpose of a fast is not to test a person's endurance, punish the flesh, go on a diet or be healthier, but rather to focus more on God such as in prayer.  Fasting is not a hunger strike that manipulates God.  Fasting changes us rather than changes God.  Fasting shouldn't be used to afflict us or make ourselves look more spiritual.  The Jews of Jesus' days were guilty of looking gloomy and unkempt when they fasted.  Fasting should be unnoticeable by others.
(16)  "And when you fast, do not look gloomy like the hypocrites, for they disfigure their faces that their fasting may be seen by others. Truly, I say to you, they have received their reward (17)  But when you fast, anoint your head and wash your face, (18)  that your fasting may not be seen by others but by your Father who is in secret. And your Father who sees in secret will reward you.
Shad David Sluiter