CHAPTER XXVI 

 FOOD VALUES 



Always, man has had to eat to live. In earliest times 

 his main energies were devoted to hunting and gathering 

 food. Even today, with all our modern knowledge and 

 appliances, a large part of our population is engaged in 

 raising, gathering, and preparing food, and in transport- 

 ing it throughout the world to those who need it. 



Once man's body was the only machine he had to help 

 him. Now he makes machines by which he controls the 

 forces of nature. But, though his own physical effort is 

 lessened as a result, his own bodily machine is just as im- 

 portant to him as ever. It must not only be kept alive, 

 but it must be kept in good running order, and be fed the 

 right food fuel that it may produce the greatest energy 

 possible. 



It is clear, then, that one of our most important 

 acts is eating. Careless eating, overeating, or eating the 

 wrong food may clog our bodily machinery, causing it 

 to lose strength and efficiency. For our comfort, suc- 

 cess, and best usefulness we need to know how and what 

 to eat. 



In the constant motion of the muscles and in the activities 

 of all the other organs of the body, there is a continual loss of 

 heat and of the material of which the body is composed. In con- 

 sequence of this loss, the tissues must be renewed and new force 

 provided to keep them in action. Otherwise all the muscles will 

 waste away and all activity will cease. Hence the necessity of a 

 constant supply of new substances that will furnish building 

 material and energy. These substances are called food. Food 

 may be denned as a substance containing material necessary for 

 the growth of the cells of the body, or as the fuel that, when 

 oxidized, produces the energy needed to carry on the processes of 

 the body. Any substance that is unable to accomplish one of these 

 purposes cannot properly be called food. 



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