CHAPTER XI 

 THE HYGIENE OF DIGESTION 



Food in relation to age. The amount of food suffi- 

 cient for the body's needs varies with age and with 

 activity. The active growing child requires food not 

 simply to produce energy but to build up his tissues. He 

 therefore requires more food in proportion to his weight 

 than the adult, who needs the food principally for the 

 production of energy. The aged person, whose activity 

 is slight and whose tissues are changing but slowly, 

 needs but comparatively little food. 1 



To health. The amount of food required also varies 

 with the general condition of the body, that is, whether 

 it is healthy or ill. In illness, not only is muscular ac- 

 tivity less, but the ability to digest may be so far reduced 



The heat units used represent the amount of heat necessary to 

 raise certain amounts of water one degree Centigrade. 

 1 Calorie = 1 kilo water, 1 C. = 1 Ib. water, 4 F. 



1 calorie = 1 gram water, 1 C. =0.001 Ib. water, 4 F. 



1 micro-calorie = 0.001 gram water, 1 C. = 0.000001 Ib. water, 4 F. 

 1 Calorie is equivalent in mechanical energy to 1.53 foot-tons. 



1 calorie " " 3.06 foot-pounds. 



120 



