According to those who hold that the bread and wine do not merely represent the body and blood of Christ, but actually are those things, why are those things eaten?
Should they not be buried?
Why are we "eating" the flesh and blood of Christ?
1. Because Jesus commanded us to
In the institution of the Eucharist, Jesus explicitly commands us to eat the bread and drink the wine, saying "This do in remembrance of me." Indeed, as often as we do this, we do "proclaim the Lord's death until He come."
Indeed, John goes even further, recording Jesus in dialogue saying:
The fact that Christians "ate the body of Christ" and "drank his blood" led to the belief in ancient Rome that Christians were cannibals. This was one of the reasons they were persecuted. That said, the point was that Christians were completely identifying with Christ, and not just filling the belly.
2. Because Priests consume the sacrifice
1 Corinthians 5 says:
This indicates that Christ, being the Passover, is the sacrifice. As a "royal priesthood," the pattern would be to handle the sacrifice as was custom. In Dueteronomy 18:1, we read of the Levites:
Another meaning of eating Christ's flesh regards the Passover. Just before the exodus, the Hebrews were commanded to kill a lamb without blemish (i.e. "perfect") and use the blood to paint their doorposts and lintels so that God's angel would "pass them over" and not strike their firstborn sons dead (Ex 12). They were also commanded to remember this event every year and pass this story on to their children (Ex 13:14).
The Last Supper was a passover meal. At it, Jesus broke the unleavened bread that they were eating and established the eucharist, saying it was his body. There's some symbolism here regarding Jesus being the Passover lamb that saves us from death.
Not being familiar with the teaching of transubstantiation, I can only refer you to Jesus' own words in this regard, as recorded in John 6:63. I'll include those words here and then comment on them.
Not only were Jesus' fellow Jews in the synagogue where He uttered the words about the necessity of eating His flesh and drinking His blood (see Affable Geek's block of text in yellow, above) offended, but
The offense taken by the Jews, and the grumbling evidenced by many of Jesus' disciples were triggered by their failure to realize Jesus was speaking in spiritual, not physical terms. Put differently, Jesus was speaking in metaphorical, not literal terms.
Jesus often used this tactic, if you will, for a number of reasons:
Just as Jesus' parables were designed both to offend people and to expose their unbelief, so also was His teaching on the bread of life, with its reference to eating His flesh and drinking His blood.
In conclusion, Jesus and His hearers were on different wavelengths, spiritually speaking, and Jesus used the hyperbole of His words to speak life into their lives. Again,