And when he had fasted forty days and forty nights, he was afterward hungry.
All Commentaries on Matthew 4:2 Go To Matthew 4
Theophylact of Ochrid
AD 1107
He fasted to show us that fasting is a great weapon against temptations, just as the love of delicacies was the beginning of all sin.
He fasts as long as Moses and Elijah did, for if He had fasted longer, it would have seemed that He had taken flesh in appearance only.
He hungered only when He permitted His nature to do so, to give the devil an opportunity through hunger to approach Him and engage Him in combat, so that Christ could throw him down and vanquish him and grant us the victory.