There is a whole branch of linguistic science about metaphors. You do not have to have a particular direction from “left to right,” as it were, to set up a comparison that functions as a metaphor.
For example, if I say, “This is my little angel,” as I show you a picture of my granddaughter, this is what is called a gestural metaphor, taking a physical object and referencing it with the demonstrative pronoun “this.” Every ordinary user of English would know the picture is not my daughter, nor an angel per se. But they would know exactly what I intended to communicate about my daughter. Therefore metaphor. It’s automatic, unless it’s controversial.
Peace,
SR
So how does “This My Body” function as a metaphor? What does the “My Body” illuminate about the bread? Because the sentence is about the bread.