SEC. 4. ON DIET. 



550 An ordinary man living an ordinary life will need for 

 the maintenance of vigorous health a certain amount of food of a 

 certain kind ; this we may take as a normal diet. 



Presuming that the experience of man has led him to adopt 

 what is good for him, we may ascertain approximately the normal 

 diet by means of the statistical method, by examining the nature 

 and amount of the daily food of a very large number of individuals. 

 The most valuable data for this purpose are those gained by 

 inquiries among persons who choose their own food ; the results 

 gained from the diets used in prisons or other institutions, or among 

 bodies of men such as the army, though more readily arrived at, 

 are open to the objection that the diets in question are determined 

 in part by the theoretical opinions of those whose duty it is to rix 

 the diet. Putting together the various statistical results thus 

 obtained, and selecting the quantities which seem to be most 

 commonly used rather than attempting to strike a strict average 

 or take a strict mean, we- find that in an ordinary diet for the 

 twenty-four hours the several food-stuffs are 



Proteids from 100 to 130 grms. 

 Fats 40 80 



Carbohydrates 450 550 



1 i these we must add 



Salts 30 grms. 

 Water 2800 



The total (available) potential energy of the lower estimate is 

 2G10, of the higher 350-5 (kilogramme-degree) calories, calculated, 

 in round numbers, on the data of 527. With such a statistical 

 diet we may compare an experimental diet, that is to say a diet 

 arrived at through a series of trials on an individual man whose 

 body might be taken to be an average one, that diet being 

 considered a normal one in which the body, maintaining vigorous 

 h'-alth, neither gained nor lost in weight, and remained moreover 



F. 53 



