A NORMAL DIET 391 



Within any one group, the energy content of the food consumed is 

 almost as proportional to the body weight as the basal metabolism is found 

 to be (Harris and Benedict). The factors, such as varying body form, 

 differences in activity of endocrin glands, that account for the latter will, 

 probably, also explain the latter. The effect of variations in body weight 

 in the same individual upon the amount of food required to maintain a 

 particular body weight will be considered later. (Page 414.) 



Influence of Work. Reference has been made to the variations in 

 energy requirement with differences in the amount of muscular work 

 performed. The amount of energy expended in a given task or occupation 

 by different individuals has been measured in several instances but the 

 results are rather conflicting. Much depends upon the previous training 

 and experience of the individual, but even with individuals of similar his- 

 tory, the amount of energy expended in the same occupation varies tremen- 

 dously (Becker and Hamalainen, Lusk(^), 1917, Sherman(c), 1918, Ben- 

 edict andCathcart andWallerand associates(a) (b) (c)). To a considerable 

 extent, this variation is probably due to differences in the amount of work 

 accomplished, but other factors may also play a part. Nevertheless, it still 

 remains true that typesetters and cobblers do less work than machin- 

 ists and that business and professional men do not use their muscles as 

 much as farmers or laborers. And, consequently, men whose occu- 

 pations involve muscular exercise do not usually eat so much as do 

 those who do much physical work. In some of the observation* con- 

 solidated in Table IV, this fact may be obscured by three other factors. 

 Of these, the influence of body weight has already been discussed. Of 

 possibly equal significance is the fact that the reports are not only for 

 individuals but for groups and families. The very large food consump- 

 tion of a laborer doing hard work may no longer be so apparent when the 

 only report is that for the food consumption of the family. It may be that 

 the family of a man who is engaged in hard work will be similarly more 

 active but it certainly is not always the case. (See also discussion of Sund- 

 strom's results, pages 3 67-3 GO.) 



The influence of mental work upon food intake may be neglected. 

 There is no evidence that mental work, even of the most fatiguing nature, 

 appreciably affects the amount of metabolism. Starling(&) (1919) has 

 suggested that mental work, while not requiring much energy, may require 

 that to be supplied at a high pressure. This would justify a liberal pro- 

 tein and energy allowance in the food of brain workers. 



Influence of Economic Status. Last, but not least, is the economic 

 factor. Beginning with EngePs figures and proceeding down the table, 

 one can see that in every instance in which information as to income is 

 included, except for one or two in the summary by Pearl, food con- 

 sumption increases with increase in income. It is important to remembez 



