When you start learning Chinese, it’s likely that you’ve been told that吃了吗? (chī le ma, Have you eaten?) is a common Chinese greeting.
You’ve likely been told that the reason Chinese people used “吃了吗?” as a greeting was mainly because food is the most important thing. However, after a bit of research, I found the origins of 吃了吗 to be much more interesting.
In Northern Song Dynasty (960 - 1127 A.D.), a book called Lü Convention 《吕氏乡约》written by the Lü brothers in Lantian, Shaanxi was popular among the village people in the nation. As it was a book of etiquette, it introduced common manners and protocols in daily life, including proper greetings. Among them, one rule reads:
In other words, one should avoid visiting people’s homes when they are having a meal. To ask “have you eaten?” would be the most considerate thing to do.
Eventually this phrase caught on and became a daily greeting. By asking “吃了吗？”, you are showing that you care about the other person and it would be easy to start a conversation. However, as you may have noticed, it is not used as often any more. If you are ever asked “吃了吗”, just a simple “吃了 ( chī le,I have)” or “没吃 (méi chī, I have not)” would do.