What does it mean that "people are iron rice and steel"?

Man is iron rice or steel: even if he has a stubborn will like steel, he must have the material guarantee of food.

This comes from "whether people are iron rice or steel, they will be hungry if they don't eat." As the saying goes, people are compared to iron, rice to steel, and then people are compared to rice, emphasizing that people have to eat no matter how powerful they are, which means emphasizing the importance of eating. With a teasing and humorous tone. Even if a person has a stubborn will like steel, he must have the material guarantee of food, otherwise he will be embarrassed by hunger and his will will will be less stubborn. Because the hardness of steel is greater than that of iron, the basic importance of matter is emphasized. Secondly, steel and panic are used to facilitate the spread of folk proverbs, such as tenderness and fluency.