FOODS AND THEIR USES 253 



starchy foods fattening. But no amount of starch or fat 

 would prevent a man from dying of starvation, because he 

 requires some food which contains nitrogen. 



The carbohydrates and fats, while they do not alone 

 suffice to form the living protoplasm of our body, never- 

 theless supply us with the energy that maintains our bodily 

 heat and enables us to do muscular work. Proteins also 

 supply us with energy in addition to affording all the ele- 

 ments necessary for building up living tissue. We might 

 live on protein food alone, but in order to supply the energy 

 we need we should have to eat so large a quantity of 

 protein that there would be an abnormally large amount 

 of nitrogenous waste products to be eliminated and the 

 organs of elimination would be subjected to an undue strain. 

 A varied diet is therefore best. Along with meats there 

 should be eaten fruits, vegetables and cereals in order to 

 supply the carbohydrates which afford the main source of 

 our energy. Milk, the sole food of the infant, contains 

 proteins, fats and carbohydrates in about the proper 

 proportions. Most of the proteins of milk may by proper 

 methods be converted into cheese. After the milk stands 

 the fat rises as cream to the surface and may be made into 

 butter. The carbohydrates are mainly in the form of 

 milk sugar or lactose. 



The kind and amount of food needed depends upon 

 climate, habits of life and the peculiarities of the individual 

 person. The Esquimaux may eat much more fats and 

 carbohydrates than would be good for men in a temperate 

 climate because they need food that can be utilized as fuel. 

 A man at hard labor may likewise utilize more of these 

 kinds of food than the gentleman of leisure. Perhaps 

 most of us eat rather more than is necessary, and it is 

 certain that overeating is a fruitful source not only of 

 disturbances of digestion, but of various other bodily 



