I know protestants dislike to hear this–but it is a mystery! The word sacrament means mystery. Jesus says: This is my body and this is my blood, and we believe Him! It does not matter that it still looks and tastes like bread and wine–we believe that it is the “Real Presence” of Jesus Christ in the Holy Eucharist. We take Jesus at His word!
After the disciples had eaten the new and holy Bread, and when they understood by faith that they had eaten of Christ’s body, Christ went on to explain and to give them the whole Sacrament. He took and mixed a cup of wine. Then He blessed it, and signed it, and made it holy, declaring that it was His own Blood, which was about to be poured out. …Christ commanded them to drink, and He explained to them that the cup which they were drinking was His own Blood: 'This is truly My Blood, which is shed for all of you. Take, all of you, drink of this, because it is a new covenant in My Blood, As you have seen Me do, do you also in My memory. Whenever you are gathered together in My name in Churches everywhere, do what I have done, in memory of Me. Eat My Body, and drink My Blood, a covenant new and old."
St. Ephraim Of Syria