Which human flesh has ever consisted of literal bread?
That is not what transubstantiation means. Please read about it here, in order to increase you understanding of it:
"Transubstantiation" by Frank J. Sheed
Hopefully, this will substantially alter your apparent very low opinion of both the veracity of Jesus and the power of God (which is limitless -- as the tagline of Salvation says, "With God all things are possible." Matthew 19:26).
Have to stop posting for the night -- I sincerely hope you read that linked page and then understand it much better.