Luke 4:4

"And Jesus answered him, 'it is written, man does not live on bread alone'".

Jesus' answer to satan tempting Him with creating bread. Jesus responds with scripture (from Deuteronomy) that life is not all about the physical, but rather obedience to God's will (in this case, to stand firm and persevere). In John 4, the disciples try and get Jesus to eat, but He replied:

"I have food that you know nothing about...my food is to do the will of Him who sent me"

So again Jesus fasts seeing the physical as not everything that matters, and pressing into obeying God.
In Ephesians 6, it says put on the armour of God to stand against the enemy including the "sword of the Spirit, which is the Word of God". Jesus had the Word (scripture) to rebuke the enemy's lies and the Holy Spirit to discern and resist Satan.

Are you feeling attacked by the forces of darkness? Tempted from the truth? Immerse yourself in scripture to gain truth, and invite the Holy Spirit to live in your heart. He is God, and will guard and empower you.