CHAPTER 7 • WHAT KINDS OF STUFF SERVE AS HUMAN FOOD? 



1 Can we trust our instincts or feelings in deciding what to eat 



and how much to eat? 



2 Can we Hve on vegetable diets only or on meat only? 



3 Will eating meat make us strong? 



4 Does sugar yield quick energy? 



5 Are "sweets" harmful? 



6 Do restaurants and hotels serve balanced meals? 



7 What foods are fattening? 



8 How did our grandparents get along without knowledge of 



vitamins ? 



9 Are irradiated foods better than others? 



We should expect that in half a million years or more the human race 

 might have learned all there was to know about what to eat and how to 

 eat it. Most people, however, do not know, either from instinct or from 

 daily experience, the best way to manage their personal food problem. 

 Everywhere children suffer from defective nutrition, and grown folks from 

 disturbances of digestion. Starvation and overfeeding exist side by side. 

 In the course of ages we have found that some parts of animals and plants 

 (muscle, grain) are better than others (hide, wood). Customs have se- 

 lected the plant and animal materials that are most valuable as food — in 

 any given region. We are constantly discovering useful food plants and 

 food animals. But experience has not taught us the best proportions or 

 combinations of meat and grain and fruit for bodily comfort and efficiency. 



What Are the Food Needs of the Body? 



Energy to Keep Going Like all chemical processes, metabolism results 

 both in breaking down some compounds and in building up other com- 

 pounds. Metabolism leads in part to the formation of new protoplasm and 

 tissues, and in part to the breaking down of proteins and other complex 

 substances. 



The rate at which the chemical transformation or metabolism goes on 

 varies from one kind of tissue to another. It varies also with the activity of 

 the body from time to time. In a person running to a fire, the chemical 

 activity is high. During sleep or rest the metabolism is at its lowest level, 

 and is pretty constant. This low, constant level represents the basic need 

 for energy. 



The amount of food one needs for growth varies in the course of his 

 lifetime. During the first year of life the baby grows very rapidly (see illus- 



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