In the Beatitudes (meaning happiness) which is the part of famous Sermon of the Mount recorded in the Gospel of Matthew and also in Gospel of Luke, Jesus (peace be upon him) describes the qualities of the citizen of the Kindgom of Heaven, in the realm of Unmanifest. Jesus Christ blesses all who fast by saying,
"Blessed are those who hunger and thirst for righteousness, for they shall be satisfied." (Matthew chapter 5, verse 6)
'This hunger and thirst for righteousness' is exactly what fasting is. Here Jesus Christ so beautifully not only define what and how fasting should be, but also blessed the practice of fasting as well. The word righteousness holds the key to understanding the significance of fasting.
Not only in words, Jesus Christ himself also fasted (Matthew 4:2) in the spirit of surrrender to God, to be close to God and to attain the righteousness.
:: Beatitudes in Wikipedia //:: BibleGateway