"'Eat the food as you would a barley cake; bake it in the sight of the people, using human excrement for fuel.' The Lord said, 'In this way the people of Israel will eat defiled food among the nations where I will drive them.'" NIV translation
Nobody would want to eat food that has been cooked over a fire of human waste but God is warning His people that it is going to happen. When God removes His blessing from the people they will do whatever they have to do in order to survive. God is the same today in that, if we continue to disobey, He will remove His blessing from us as well. He does it not to punish us but to draw us back closer to Him.
"Then I said, 'Not so, Sovereign Lord! I have never defiled myself. From my youth until now I have never eaten anything found dead or torn by wild animals. No unclean meat has entered my mouth.'" NIV translation
Ezekiel does not want to do what God said and we have probably all been there as well. When we don't want to do what God says, it is usually because of our own selfish desires. That is not the case in this verse as we see that his reason is that he has never dishonored God in this way and does not want to start now.
"'Very well,' he said, 'I will let you bake your bread over cow manure instead of human excrement.'" NIV translation
There are those that say that God does not change His mind but, as we see with this verse, God does listen to us and will change His mind sometimes.
"He then said to me: 'Son of man, I will cut off the supply of food in Jerusalem. The people will eat rationed food in anxiety and drink rationed water in despair, for food and water will be scarce. They will be appalled at the sight of each other and will waste away because of their sin.'" NIV translation
God is going to cut off the supply of food and water from Jerusalem since they did not give Him the glory for providing it. They will look at each other and be shocked at the sight of what happens when God removes His hand of blessing.