A little background is needed before we discuss what the Bible says about this unique bread. The prophet Ezekiel was commanded to make a miniature version of Jerusalem and surround it with besiege towers and battering rams. He was then to take an iron pan and lay siege to it!
He was commanded to partake of this mock seize 390 days while on his left side and for 40 days while on his right. This symbolized the number of years Israel and Judah were to be punished (Ezekiel 4). During the first part of his mock siege, he was to eat only food based on the following recipe.
Take also to yourself wheat, and barley, and beans, and lentils, and millet, and spelt, and put them in one vessel, and make bread of them for yourself . . . (Ezekiel 4:9, HBFV throughout).
The beans and lentils Ezekiel used to make bread were two of the most widely eaten vegetables in Israel. Millet is a small summer grain that, of itself, makes for a poor quality loaf. Spelt is an inferior type of wheat that is referred to as "rie" in the KJV (Exodus 9:32, Isaiah 28:25). Barley was cheap to buy (see Ezekiel 4:10 - 12). It was often bought by the poor to make loaves that were heavier, but less tasty, than those that were wheat based.
Why was the prophet given such an odd recipe? It was to symbolize the famine conditions that would be extant in Jerusalem during an actual siege. God commanded the prophet eat only twenty shekels' weight of food (about ten ounces or 228 grams) and drink only a sixth of a Hin of water (about 1 1/3 pints or .6 liters) each day. This was barely enough to keep him alive.
Ezekiel was initially commanded to make this special bread over a fire created by burning human excrement (Ezekiel 4:12). He so loathed burning human waste that he got God to allow him to cook with cow's dung instead (verses 14 - 15).
We do not have to wonder why the Eternal allowed his people to suffer being attacked and endure a prolonged famine. The last two verses of chapter four tells us it was because the people refused to repent of their sins.
And they shall eat bread by weight, and with care. And they shall drink water by measure, and in silence . . . and be appalled with one another, and waste away for their iniquity (Ezekiel 4:16 - 17).
The bread of Ezekiel did not symbolize abundance. Its ingredients were not meant to be a new formula for creating a healthier loaf that is somehow better to eat than others.
Instead, Ezekiel's bread speaks of scarcity and the need to gather up whatever scraps can be found in order to survive. Such a loaf of poverty and affliction should not be reproduced in modern times. It represents the suffering and trials of those who refuse to repent and begin to obey God. In the final analysis, what Ezekiel had to eat was the Eternal's judgment and punishment of sin!