After entering middle age, the human body consumes more calories than it consumes, and the excess energy substances are converted into fat and stored in various tissues and under the skin, and people gradually become fat, which is a normal physiological change in the so-called "fat" period. If people gradually lose weight after entering middle age, it is often an ominous sign. Although inflammation or ulcer of oral cavity, stomach, intestine, liver, pancreas and other organs can cause digestive and absorption disorders and lead to emaciation, we should pay special attention to malignant tumors, because emaciation is a prominent manifestation of malignant tumors. Therefore, once middle-aged people suddenly lose weight, they should go to the hospital for examination in time and cannot be ignored.