When God does somethings he does it with the intention to teach us. Like for example when the Lord prayed, He prayed to teach us how to pray. But we believe that God is three in one, just like the sun: its ray of light, its heat, and its shape, are those separate from one another? Or do we call it the sun? When sunlight is in the Church? Did the Sun leave the sky and come into the church? Of course not. When Jesus was praying to the Father, he prayed to teach us how to pray. He also prayed before choosing his disciples. So this does not mean we believe in three Gods, its only one. God the Father is in heaven and God the Son incarnated to fulfill the salvation of the whole human race. He came , was incarnate, crucified to save all of humanity. This means when Jesus prays there is no division between God the Father, God the Son, and God the Holy Spirit. "Believe Me that I am in the Father and the Father in Me". When Jesus fasted it is was also done for the same reason so that we can learn from his actions. Jesus does not need to fast.