NORMAL DIET 583 



It will be observed that the habitual performance of hard physical 

 labor is correlated with a high calorific intake. The increase of intake 

 affects, as a rule, all three classes of foodstuffs. The increase of the 

 Protein intake is surprising in view of the fact that proteins are not 

 a normal source of muscular energy. This apparent contradiction, 

 which has been observed in all countries, has been explained in several 

 diverse ways. Advocates of a high plane of protein nutrition have 

 advanced the tendency to increased consumption of protein by those 

 who perform hard physical labor, as evidence that the increased speed 

 of metabolism induced by protein facilitates the functional activity of 

 the tissues, including muscular tissues. Advocates of the low plane of 

 protein nutrition, on the contrary, have urged that the high protein 

 intake of these persons is essentially accidental, arising simply from the 

 fact that they ingest larger quantities of all foodstuffs and, maintaining 

 the normal admixture of the three types of food material, incidentally 

 consume more protein. This, however, was certainly not true in the 

 case of the blacksmith and the professional athlete, Sandow, whose 

 dietaries were investigated by Atwater. A more reasonable suggestion 

 than either of the above is probably that which has been put forward by 

 Voit, that as persons accustomed to hard labor are usually more muscu- 

 lar than sedentary individuals, the total protein intake required to 

 support the greater quantity of Protoplasmic Tissues, maintaining their 

 wear and tear, and at the same time the exogenous metabolism, is 

 greater than it is in persons, even of like weight, in whom a considerable 

 part of the weight is made up of adipose tissues, for example. The 

 figures obtained by Atwater are certainly suggestive from this point of 

 view, for the total mechanical work performed by Sandow in a brief 

 daily exhibition and a period of practice or exercise was evidently not 

 nearly equal to that performed by a manual laborer in an eight- or ten- 

 hour day. But by exercises and a mode of life carefully directed to 

 that end, Sandow had brought about in himself an extraordinary degree 

 of muscular development, far exceeding that of the ordinary laborer, 

 in harmony with Voit's suggestion we find that his intake of protein 

 was nearly two and a half times the normal, while his intake of fat was 

 normal and his intake of carbohydrates only slightly above the the 

 average. 



It has already been pointed out that the vegetable foodstuffs are, 

 as a rule, distinguished by their relatively low content of protein. 

 This arises from the fact that carbohydrates assume a structural role 

 in plants \vhile in animals their place as structural materials is taken by 

 proteins. It is from this fact that one of the several objections to 

 the practice of Vegetarianism arises. A purely vegetable diet is, if 

 nitrogenous equilibrium is maintained, an exceedingly voluminous one. 

 The indigestible residues of cellulose are large, the feces very bulky, 

 and the fecal masses occlude a proportion of otherwise digestible and 

 assimilable materials which are voided with them. The wastage in a 

 vegetarian diet is for this reason alone a considerable item. A much 



