It refers to the pathological changes where food stagnates in the stomach, leading to the generation of dampness and heat. Where there is retention of food, it is mostly due to the inability of the transmission and transformation of food and drink, which is the essence of the pathological changes. It is often caused by overeating and excessive drinking, exceeding the capacity of the spleen and stomach to receive and transport. The pathological changes are mostly reflected in the following three aspects: obstruction of qi movement, abnormal ascending and descending; stagnation of food leading to the generation of dampness and heat; and deficiency caused by stagnation, leading to injury of the spleen and stomach. The stomach is one of the six fu-organs, which functions by being unobstructed, should be full but not overflowing, and should discharge without storing. If food stagnates, it will inevitably affect the smooth movement of middle energizer qi, causing abnormal ascending and descending of the spleen and stomach, leading to blockage in the chest and epigastric fullness, abdominal distension and fullness with occasional pain; failure of the stomach to descend, leading to turbid rising of qi, causing belching, acid regurgitation, or even vomiting; and obstruction of transmission, leading to diarrhea or constipation. If food accumulation is not digested, it will generate heat, resulting in dampness-heat retention of food, and dysfunction of the middle energizer's ascending and descending, leading to vomiting, belching with foul-smelling food above, and foul-smelling diarrhea below. If the spleen and stomach are inherently weak, and there is food accumulation stagnation, or long-term retention of food, leading to deficiency caused by stagnation, it often presents as a spleen deficiency with food stagnation, a pathology of deficiency mixed with excess. In addition to the aforementioned symptoms of food stagnation in the stomach, there are often symptoms such as loose stools, reduced appetite, mental fatigue, weakness in the limbs, pale tongue with greasy coating, and weak pulse. Since this pathological process of deficiency caused by stagnation and stagnation caused by deficiency coexist and influence each other, it often has the characteristic of recurrent episodes and prolonged unhealing.