Effect of Age on the Body's Tolerance 



143 



which occur during the growth period; in each case average 

 normal values for body composition and content were used 

 (Shohl, 1939; Forbes and Perley, 1951; Corsa et ah, 1956; 

 Friis-Hansen, 1957). Each substance has been considered 

 separately. In dealing with water, sodium and potassium, 



DAYS OF 

 DEPRIVATION 

 TO PRODUCE 



SERIOUS 

 DEPLETION 



15% DECREASt IN BODY PROTEIN 

 LOSS = 259m/m2/24"' ? 9 



15% DECREASE IN BODY SOOiUM 

 LOSS = 10 TiEq/m^/gA* X X 



75% DECREASE IN BODY FAT (CALORIC) STORES 

 LOSSnaoOCal /m2 /2A' f V 



15% DECREASE IN BODY POTASSIUM 

 LOSS = lOmEq/nn2 /24' O— O 



15% DECREASE IN BODY WATER 

 STORES •— • 



LOSSES' IWL + OBLIGATORY URINE 



/ 6 3 6 9 12 18 2 

 BIRTH WKS --MONTHS^ 



3 4 6 6 10 12 16 20 

 YEARS ■ 



Fig. 3. Days of deprivation (ordinate) needed to produce the 

 percentage decrease in body content indicated for each 

 substance in individuals of various ages (abscissa). The 

 rates of loss indicated for each substance approximate to 

 physiological minimum output rates, of which some are indi- 

 cated by the lower boundaries of the physiological tolerance 

 ranges shown in Fig. 2. 



rate of loss was taken as the physiological minimum require- 

 ment value indicated in Fig. 2. In considering body fat 

 (calorie) stores, energy expenditures were assumed to be at 

 the rate of 1,800 calories per m.^ per day (Macy, 1942) and to 

 be derived entirely from body fat. Body protein losses were 

 calculated assuming a basal rate of loss amounting to 25 g. 

 per m.2 per day, the minimum value attained by individuals 



