The basal metabolic rate varies with gender and age. The average basal metabolic rate of men is higher than that of women, and that of children is higher than that of adults. The older you get, the lower your metabolic rate is. Generally speaking, the difference between the actual value of basal metabolic rate and the normal average value is within 10- 15%. When it exceeds 20% of the normal value, it can be considered as a pathological state. In hypothyroidism, the basal metabolic rate is 20-40% lower than the normal standard; In hyperthyroidism, the basal metabolic rate is 25-80% higher than the normal standard. When other functions such as adrenal cortex and pituitary gland are low, the basal metabolic rate will also decrease.
The minimum energy required to sustain the life of an organism.
The abbreviation of B.M. The minimum energy required to sustain the life of an organism. In order to eliminate the extra energy consumption (called functional consumption) caused by muscle work, mental activity, food digestion and temperature regulation of external temperature changes, subjects should keep absolutely quiet and fast (people don't eat within 12- 18 hours), and the energy consumption at critical temperature is taken as the basic metabolic quantity. 1 natural annual human basal metabolism is 1200- 1400 kcal in Japan and 1500-2000 kcal in Europe and America, but due to the influence of daily life style, the number of kcal is not absolute. Basic metabolism inevitably includes mechanical work of heart, respiratory muscle, digestive tract and vascular smooth muscle, as well as functional consumption caused by secretory activities of liver and kidney. The basic consumption caused by the life process of each cell accounts for about 3/4. The basal metabolism of the same warm-blooded animal is directly proportional to its body surface area under the same environment. A person's body surface area S(cm2) can be calculated by weight W(kg) and height H(cm) with various experimental formulas. Dubois' (19 15) formula: S=W0.245×H0.725×7 1.84 is widely used. Japanese, the coefficient of women is 72.46, and that of men is 74.49. Of course, the basal metabolic quantity per unit body surface area also changes with age, sex, time of day 1, season, nutrition, physique, medication, pathological state and so on. People are the lowest at birth, then increase rapidly, reach the highest value at the age of 5, and then gradually decrease, generally staying the same at the age of 20-40 (above). Then it gradually decreases in old age. The value of adult women is 5-7% lower than that of men, because the proportion of adipose tissue in women is higher. The percentage of the difference between the measured value and the normal standard value (age, sex) to the normal standard value (increase in metabolism,-decrease in metabolism) is called basal metabolic rate (B.M.R), which is often used for thyroid function examination in clinic.
Minimum energy metabolism
At room temperature 18 ~ 25℃, the human body is in an empty stomach, lying flat, awake and quiet state, which is called the basic state. At this time, the minimum energy metabolism necessary to maintain basic life activities such as heartbeat and breathing is called basal metabolism (BM). Its value is related to gender, age, height, weight and health status. As mentioned earlier. All the energy generated by the body will eventually become heat energy, so in order to compare the energy metabolism level of different individuals, it can be expressed by the heat emitted by the body per hour per square meter of body surface area (kJ/h m2), that is, the basal metabolic rate (BMR).
The body surface area of the machine body can be obtained by the following formula:
S(m2)=0.006 1× height (cm)+0.0 128× weight (kg)-0. 1529.
Basal metabolism tester
Basic metabolometer is commonly used in clinic to measure oxygen consumption per unit time (O2L/h). Because the conditions are relatively fixed in the basic state, through investigation, the basal metabolic rate (BMR) can be obtained by substituting the mixed respiratory quotient 0.82 and the calorific value of oxygen 19.3kJ into the following formula.
BMR = O2L/h× 19.3 kj \s
For example, a 30-year-old male with a body surface area of 1.5m2 and an oxygen consumption of 1.2l/h measured in the basic state, then
BMR = 12L/h× 19.3 kj÷ 1.5m 2 = 154.4 kj/hm2
Then calculate the percentage of excess (+) or deficiency (-) according to the normal BMR of other age groups in Table 9-3, and judge whether it belongs to the normal range (generally 10%).
Basic heat production
The basal metabolic rate of normal people is relatively constant. Generally, men are slightly higher than women, children and adolescents are higher than adults, and gradually decrease after adulthood.