It puzzled the disciples too. I have always found it helpful to look at the verses following this difficult passage.
60 Many therefore of his disciples, when they had heard this, said, This is an hard saying; who can hear it?
61 When Jesus knew in himself that his disciples murmured at it, he said unto them, Doth this offend you?
62 What and if ye shall see the Son of man ascend up where he was before?
63 It is the spirit that quickeneth; the flesh profiteth nothing: the words that I speak unto you, they are spirit, and they are life.
Jesus makes it clear he won’t be physically “eaten” - as he speaks of His actual Body (would be buried in a tomb) ascending to heaven. (V62)
Here Jesus clarifies literal Flesh is not what gives eternal life. But the word of God, every word He spoke.
Gen 1
1 In the beginning was the Word, and the Word was with God, and the Word was God.
2 The same was in the beginning with God.
3 All things were made by him; and without him was not any thing made that was made.
4 In him was life; and the life was the light of men.
Jesus is the word made flesh. Even they Clearly could not understand this at the time and so they were baffled thinking he referred to eating human flesh.
He spoke of receiving Him to themselves and in so doing, accepting the word of God and it dwelling within. The life giving eternal word. God. God is spirit! His word is spirit and life to us. His word must abide in us and produce fruit. This is the life of the spirit of God (The living word) within us. This is what it means to fully consume Christ - the word of God - that He becomes part of our very being (Just as the physical food we eat becomes part of every cell in our body and makes us grow.)
John 15
3 Now ye are clean through the word which I have spoken unto you.
4 Abide in me, and I in you. As the branch cannot bear fruit of itself, except it abide in the vine; no more can ye, except ye abide in me.
5 I am the vine, ye are the branches: He that abideth in me, and I in him, the same bringeth forth much fruit: for without me ye can do nothing.
To consume all He is for us, The truths of all He said He was, our earthly sacrifice for our sins to God and the spirit and the seed of eternal Life Within us. He is the spiritual bread of life, He is the spiritual rock in the wilderness from which life giving water flowed forth, He provides and is everything we need for eternal life. He is the word of God. He is God.
John1
11 He came unto his own, and his own received him not.
12 But as many as received him, to them gave he power to become the sons of God, even to them that believe on his name:
13 Which were born, not of blood, nor of the will of the flesh, nor of the will of man, but of God.
14 And the Word was made flesh, and dwelt among us, (and we beheld his glory, the glory as of the only begotten of the Father,) full of grace and truth.
Sorry for the lengthy reply,
But one last thought. A thought of using some plain old common sense.
When Jesus took the bread and broke it and said “take and eat. This is my body broken for you,’ were the disciples actually eating Jesus’s physical body then and there whilst He was standing - alive and whole before them? Because if the bread in His hands was His literal
Body, (or as some would have it, transformed into His body when they ate it) - ... He would have existed as a flat bread, a glass of wine, and a person all at the same time.
He would have died if He switched over to being the bread and wine upon it being consumed - or been severely wounded even if only bits of Him were consumed, and He,
Or parts of Him, would be travelling through the digestive systems of the disciples that very day (and possibly through His own Digestive system too as He was by law bidden to partake of the Passover as a Jew.) Of course I speak as a fool but to make a point.
Jesus Himself said explained that what is physically eaten does not make a difference to the spiritual state of a person.
Matt 15
16 And Jesus said, Are ye also yet without understanding?
17 Do not ye yet understand, that whatsoever entereth in at the mouth goeth into the belly, and is cast out into the draught?
18 But those things which proceed out of the mouth come forth from the heart; and they defile the man.
19 For out of the heart proceed evil thoughts, murders, adulteries, fornications, thefts, false witness, blasphemies:
20 These are the things which defile a man: but to eat with unwashen hands defileth not a man.
And Paul reiterates the sentiment though in a different context.
17 For the kingdom of God is not meat and drink; but righteousness, and peace, and joy in the Holy Ghost.