The rapid disappearance of subcutaneous fat is usually caused by immune system disorders, endocrine abnormalities, malnutrition and other reasons. 1. Immune system disorders: immune system disorders are usually caused by irregular lifestyle, long-term alcohol consumption, etc. Patients may suffer from insomnia, excessive dreams, dizziness and other symptoms, accompanied by weight loss. 2. Endocrine abnormality: endocrine abnormality generally refers to the symptoms of endocrine disorders, usually caused by environmental factors, physiological factors, such as hyperthyroidism and other high-consumption diseases, the patient may be afraid of heat, irritability, weight loss and other symptoms. 3. Malnutrition: malnutrition generally refers to the insufficient intake, malabsorption or excessive depletion of nutrients caused by the patient’s physical condition, usually caused by pathological changes, such as malignant tumors of high-consumptive etiology leading to malnutrition; intestinal fistula leading to intestinal nutrient flux; tuberculosis disease leading to excessive consumption of nutrients and so on. Rapid disappearance of subcutaneous fat may also be due to other reasons, such as large exercise consumption. Should be timely to the hospital, exclude physiological causes, clear diagnosis and follow the doctor’s instructions to be appropriate treatment.