Using the word “physical” in reference to the Eucharist produces confusion only because for most of us, “physical” means the accidents of a particular object and not its substance.
When we say something is ‘physically’ present, we usually mean that we that we can discern the object by its taste, smell, dimensions, duration, molecular structure. Philosophically, those are all accidents. They are not the substance of an object.
After the consecration the substance of bread and wine are gone. The substance of the bread and wine has been transformed into the substance of Christ. But the accidents remain. That’s why we still perceive the accidents of bread and wine. (Note that those accidents do not inhere in any substance, because the bread and wine are gone, replaced by Christ.)
After the consecration, the substance of Jesus Christ is truly present whole and entire, all of him—and yes, he has a body, not merely a “spiritual” body, whatever that may mean. So all of him is present. His whole body, his blood, his human soul, his divine nature, his divine Person.
But we do not perceive his accidents, or appearances. We perceive only the appearances of the bread and wine, whose substance is no longer present.
Because of his mode of presence, he cannot be subdivided (or multiplied). Breaking the host in half or quarters or smaller pieces does not subdivide Christ. He is wholly present under the appearances of each particle, just as the one Christ is present in each host, though he himself is not and cannot be multiplied.
If we chew up the host, we don’t destroy the body of Christ. He remains whole and entire. So cannibalism is impossible.