320 STUDIES IN ADVANCED PHYSIOLOGY. 



THE EELATIVE AMOUNTS OF THESE CLASSES OF FOODS RE- 

 QUIRED BY AN AVERAGE INDIVIDUAL AND THE 

 VALUE OF A MIXED DIET. 



The experience of every one has shown that it is not 

 desirable to limit one's diet exclusively to one kind of food. 

 If one had nothing but meat he would get much more nitro- 

 gen than would be necessary in trying to get the amount of 

 carbon which the body requires, the relative amount of car- 

 bon being so small in the proteids. If one limited his diet 

 to a substance which was rich in fats and sugars, but con- 

 tained only traces of nitrogen, he would have to eat un- 

 necessarily large quantities of fats and sugars to get the 

 proteid necessary for his body. The most sensible way, 

 therefore, of determining the composition of one's diet is to 

 take enough proteid food to give to the body all the nitro- 

 genous food it needs, and then to supply it further with the 

 necessary amounts of carbon and hydrogen, to take foods 

 especially rich in these, such as fats and sugars. 



A very natural question is: What are the relative 

 amounts of these classes of foods which an average working 

 body needs, say in a day? A great many and careful ex- 

 periments have been made and the results of these do not 

 vary materially. We may, therefore, give the average fig- 

 ures with much probability that they state the correct con- 

 dition of things. In an experiment by Pettenkofer and Voit 

 on a workingman twenty-eight years old, weighing about 

 150 pounds, it was found that when not at work he needed 



137 grams of proteid. 

 72 grams of fat. 

 352 grams of carbohydrates. 



On a day when this same workman was at regular work he 



consumed 



137 grams of proteid (same as when at rest). 



173 grams of fat. 



352 grams of carbohydrates. 



It will be noticed that the extra work entailed an extra con- 

 sumption of fat. Other observers have changed this experi- 

 ment just 'a little. They, too, found that the amount of 



