It is Catholics who assert that they are taking the words of Christ literally, which would mean that the apostles consumed the actual manifestly incarnated Christ which He said to eat, versus a christ who did not appear to be what He really was. Thus I am showing them that they do not take the Lord's words purely literally, but unlike the only manifestly incarnated Christ, whose physically John emphasizes, whose body behaved, looked, etc., and would scientifically test as human flesh and blood, they make make Christ out to be something which looks etc. like an inanimate material, and would scientifically test as bread and wine, but which actually does not, but which can decay, at which point Christ no longer exist under that appearance either.
There is nothing in the pertinent texts which should preclude to a Catholic that what the apostles consumed was the actual physical flesh and blood of Christ, but the metaphysical sacramental interpretation is read into the text out of necessity, since nothing manifestly changes when the priest utters the "words of consecration."
There is a third sense, though, and that is sacramental. That is not somewhere between metaphorical or literal, so to speak, but somewhere beyond them: more meaningful than what is merely metaphorical, more real than what is merely literal.
Which as the metaphysical Catholic interpretation, is read into the text, and is no more meaningful than the metaphorical meaning, any more that making other examples of metaphorical speech to be sacramental via a like metaphysical explanation. David plainly said that the water that his valiant men brought him from the well at Bethlehem was blood, and thus refused to drink it but poured it out unto the Lord. (2 Samuel 23:16-17) A Catholic literalist could interpret that as saying that the water was "Really" literally the blood of these men, or "Really" as per a metaphysical explanation of transubstantiation, and make that a sacramental practice, but the metaphorical meaning does not need either a plainly literal or metaphysical explanation to be most meaningful. And as such it could be a sacramental practice if it was so commanded, reminding people of how risking your life for others if like giving them your own blood.
This is why Our Lord calls His Body "real food" and His Blood "real drink." "Real" (or some translations say "true") is in contrast to what? In contrast to both metaphorical and literal.
Scripture (John 6:55) does not say that the Lord calls His Body "real food" and His Blood "real drink," but affirms that both are surely, of a truth (alēthōs), food and drink, which does not refer to what sense they are, but that they are.
And what sense they are is revealed in the light of the rest of Scripture, in which what souls receive for spiritual life is the life-giving gospel message, that being "in truth [alēthōs], the word of God," (1Ths. 2:13) with the word being called "milk" and "meat," "milk" (1Pt. 1:22; Heb. 5:12,14) by which one is born again, (Ja. 1:8) and nourished (1Tim. 4:6) and built up. (Acts 20:32) And thus rather than uniquely administering the Lord supper as food as priests, the preaching the word was the primary active function of pastors, (2Tim. 4:2) who are charged with feeding the flock thereby. (Acts 20:28)
In contrast the Lord's supper is only manifestly described in one epistle to the churches, besides the mention of "feast of charity" in Jude 1:12.
This euchastisric Body and Blood of His are so real, they are real on every Catholic...
And Hare Krishna's have their imaginations of what is metaphysically real, but neither of which are an argument that they are.
In contrasts with the word "metaphorical."
It also contrasts with "literal," or "physiological," which would, I think, imply having certain measurable characteristics ---e.g. body temperature, diffusion of gases through membranes, etc.