There are many reasons for muscle loss in the body, mainly categorized into two conditions, primary muscle loss and secondary muscle loss. Secondary muscle loss can be categorized into malnutrition, chronic diseases, diabetic myoneurogenic diseases and liver diseases. 1. Primary muscle loss: it is the aging and atrophy of skeletal muscle with the increase of age. This type of muscle loss is caused by physiological factors. 2. Secondary muscle loss (1) Malnutrition: Because of starvation or insufficient nutritional intake, resulting in malnutrition, there will be a gradual loss of muscle mass on the body. (2) Chronic diseases: such as malignant tumors, cerebral thrombosis and other diseases, the gradual depletion of the body’s muscles and weight loss, will also form the clinical symptoms of muscle loss. (3) Diabetes mellitus: insulin resistance and weight loss caused by type 2 diabetes mellitus are also common clinical phenomena. (4) Neurogenic diseases: this is mainly because the muscles lose the innervation of the corresponding nerves, can not contract the decline in muscle vitality, and at the same time the neurotrophic effect of the weakening of the relevant muscle groups do not get exercise, the emergence of wasteful atrophy, resulting in muscle loss. It is common in hemiplegia caused by cerebral hemorrhage and cerebral infarction. (5) The decrease of liver glycogen and the compensatory catabolic function of myoglycogen through gluconeogenesis lead to the decrease of muscle mass. In addition, patients with liver disease often suffer from malnutrition and limited physical activity, which may aggravate muscle loss. If the situation of muscle loss occurs, it should be timely in the doctor’s diagnosis under the cause of targeted treatment.