Dye studies were completed on a healthy man of average build to determine the distribution of water in his body. Which range is most likely to represent the percentage of his lean body mass that is intracellular water?
In a healthy man of average build, water constitutes approximately 73% of the total lean body weight. Of this water, 60% is inside and 40% is our side of cells. Thus:60% of 73% = 44% of lean body weight is intracellular water40% of 73% = 29% of lean body weight is extracellular waterThe percentage obtained when comparing water to lean body weight is somewhat higher than that obtained when comparing water with total body weight (TBW), because TBW includes fat. In a healthy man of average build, a useful estimate for TBW is "2040-60" (i.e., 20% of TBW is extracellular water, 40% of TBW is intracellular water, and together, approximately 60% of TBW is water). As the fat content of an individual increases, the percentage of body weight that is water decreases.
5% to 6%
18% to 20%
40% to 50%
60% to 70%
General physiology