The spleen and stomach are middle jiao. Chinese medicine says that kidney is the innate foundation of human body and spleen and stomach are the acquired foundation. Spleen and stomach transport the subtle Shui Gu needed by human body. However, improper diet is easy to hurt the spleen and stomach, including eating too much fat and greasy, eating too cold and eating too spicy, which will cause problems in the middle energizer and affect the function of other organs. That's probably what it means.