You've got to IGNORE Jesus' words 37 verses earlier to continue on with the Transubstantiation Theory...
Jesus answered, The work of God is this: to believe in the one he has sent.
So - when the One He has sent asks you to eat His Body and drink His blood, why don't you take Him at His word?
Why not, you know, believe Him?
Your reply is a joke. Jesus then goes on to say that you need the bread that God provides. The entire rest of the chapter is dedicated to eating Jesus’ body.