From the encyclical Ecclesia De Eucharista by the holy father, John Paul II:

The
acclamation of the assembly following the consecration appropriately ends by
expressing the eschatological thrust which marks the celebration of the
Eucharist (cf. 1 Cor 11:26): “until you come in glory”. The Eucharist is a straining towards the goal, a foretaste of the
fullness of joy promised by Christ (cf. Jn 15:11); it is in some way the
anticipation of heaven, the “pledge of future glory.” In the Eucharist, everything speaks of
confident waiting “in joyful hope for the coming of our
Saviour, Jesus Christ”. Those who
feed on Christ in the Eucharist need not wait until the hereafter to receive
eternal life: they already possess it on earth,
as the first-fruits of a
future fullness which will embrace man in his totality. For in the
Eucharist we
also receive the pledge of our bodily resurrection at the end of the
world: “He who eats my flesh and drinks my blood has eternal life, and
I
will raise him up at the last day” (Jn 6:54).
This pledge of the future resurrection comes from the fact that the flesh of
the Son of Man, given as food, is his body in its glorious state after the
resurrection. With the Eucharist we digest, as it were, the “secret” of the resurrection. For this reason
Saint Ignatius of Antioch rightly
defined the Eucharistic Bread as “a medicine of
immortality, an antidote to death”