Jesus said we would fast, and I do feel lead by the Holy Spirit to fast occasionally. I believe strongly fasting can cause us to break through into new spiritual freedom, insights and revelation. The spiritual man is strengthened.
I have found it important to pray about the fast asking for His strength and guidance as to how long the fast should last. (usually till my wife says dinner is ready)
Luke 5:35 But the days will come when the bridegroom will be taken away from them; then they will fast in those days.”