24 It may perhaps be said, 'We find Him giving way to weeping, to hunger and thirst: must we not suppose Him liable to all the other affections of human nature?' But if we do not understand the mystery of His tears, hunger, and thirst, let us remember that He Who wept also raised the dead to life: that He did not weep for the death of Lazarus, but rejoiced; that He Who thirsted, gave from Himself rivers of living water. He could not be parched with thirst, if He was able to give the thirsty drink.
Again, He Who hungered could condemn the tree which offered no fruit for His hunger: but how could His nature be overcome by hunger if He could strike the green tree barren by His word? And if, beside the mystery of weeping, hunger and thirst, the flesh He assumed, that is His entire manhood, was exposed to our weaknesses: even then it was not left to suffer from their indignities. His weeping was not for Himself; His thirst needed no water to quench it; His hunger no food to stay it.
It is never said that the Lord ate or drank or wept when He was hungry, or thirsty, or sorrowful. He conformed to the habits of the body to prove the reality of His own body, to satisfy the custom of human bodies by doing as our nature does. When He ate and drank, it was a concession, not to His own necessities, but to our habits.
Source: On the Trinity (New Advent)