CHEMICAL CONSTITUENTS OF BODY AND FOOD. 39 



A diet, to be sufficient, must be adapted to the particular indi- 

 vidual's need, keeping in mind, also, the climate, age of person, and 

 the amount of work done by him. 



We make changes of clothing to suit the weather conditions in 

 order that the body may not suffer in regard to the surrounding tem- 

 perature, and our diet should be regulated with the same ends in 

 view. In cold weather we eat more, to furnish an extra amount 

 of heat; in warm weather we eat less than usual. A growing youth's 

 body must not only repair the daily waste, but also assist in con- 

 structive metamorphosis, or growth, so that he requires relatively 

 more food per diem than the adult. Because of the waste attending 

 action, the workingman requires more than the ordinary supply of 

 food. 



There are some single foods which contain all the necessary 

 proximate principles in proper proportions, but they are the excep- 

 tions, rather than the rule. Thus milk and eggs are classed as per- 

 fect foods. It is usually necessary for a proper diet to contain a vari- 

 ety of substances in this list. 



For a man doing a moderate amount of work, it has been com- 

 puted that it is necessary that the daily diet should contain the fol- 

 lowing amounts : 



Proteid 125 grams. 



Fat 50 grams. 



Carbohydrates 500 grams. 



Alimentary substances comprise products of both animal and 

 vegetable kingdoms. The principal ones are animal substances, with 

 cereals, potatoes, drinks, condiments, cocoa, coffee, tea, etc. 



The animal substances, or foods, comprise: (1) meat, (2) 

 eggs, and (3) milk, with its derivatives cream, butter, and cheese. 



The parts of animals used for food are the various portions of 

 their muscular system. They comprise the general term meat. Ani- 

 mal food, being identical with the body structures, requires nothing 

 to be added or subtracted to make it fit to give proper nourishment. 



MEAT. 



The more compact the fiber, the less digestible the meat. Hence 

 ham is much less digestible than other meats. The more fat that is 

 combined intimately with the fibers, so much less is the digestibility 

 of the meat, because the fat melts and coats the fibers of the meat 

 with a layer of oil which prevents the ferment from acting upon it. 



