Human body composition as related to surface area.
There is a linear relationship between extracellular fluid and body surface area in man. During growth the body cell mass, fat-free solids, and body fat proportions of body weight increase while the extracellular fluid fraction decreases. Growth stops in men as soon as the body cell mass reaches 22.5 kg/m2 body surface area and in women when it reaches 16.9 kg/m5. The non-muscle cell mass and the muscle cell mass reach a 1:4 ratio in men whereas in women a 1:35 proportion--which is more favorable for pregnancy and lactation--is reached. The body composition of the newborn and the infant have fetal characteristics with a low body fat: surface area ratio and a low non-muscle cell mass: surface area ratio. The basal metabolic rate depends on the amount of non-muscle mass present, and the total energy change depends on body cell mass. This has been established by measurements of total body potassium, thiosulfate space, total body sodium, 24 h urine creatinine values and basal metabolic rate.
D000273:Adipose Tissue; D000328:Adult; D001823:Body Composition; D001830:Body Surface Area; D001835:Body Weight; D005110:Extracellular Space; D005260:Female; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D008297:Male; D009132:Muscles; D012737:Sex Factors