We believe that in the Mass the bread and wine are transformed into the Body and Blood of Christ. The consecration of the Mass gives us the Body of Christ as our spiritual food, however, that was not Our Lord's purpose in making himself present for us.
We must see the Mass as following the ritual of Jewish sacrificial meals. The sacrifice had three steps. The first step, known by its Greek name of the Anamnesis, had Jesus as a worshipper, thanking God for his many favors. The second step, known by its Greek name of the Epiclesus, had Jesus and his followers putting themselves in the presence of God. The third step, known by its Greek name of the Eu-charis, had Jesus giving God his love and obedience as a sacrifice.
At the Last Supper it was when Jesus was about to sacrifice himself to God, that he gave his body and blood to the Apostles so that they could physically part of his sacrifice, of his Eu-charis
Likewise, in the Mass the principal reason for Jesus giving himself to us is not to nourish us with the Blessed Sacrament, but to make us body and soul one with him in his sacrifice.