Basal metabolism is usually assessed using the basal metabolic rate (BMR), a specialized testing instrument commonly used in clinical practice to calculate what the basal metabolism is. Basal metabolic rate is the amount of energy consumed by the body per unit of time in the basal state. The so-called basal state refers to the state of the body when it is awake, quiet, and unaffected by factors such as muscle activity, ambient temperature, mental stress, and food. In the determination of BMR subjects remain awake, lying down, muscle relaxation, no strenuous exercise for at least 2 hours, no mental stress, 12 to 14 hours after food, and the room temperature is maintained at 20 to 25 ℃. BMR, in addition to being related to body surface area, varies according to the sex and age of the subject. Generally, the mean value is higher in males than in females of the same age group; it is higher in children than in adults, and the older the age, the lower the metabolic rate. It is recommended to visit the hospital if abnormalities of basal metabolism occur.