10 VITALITY AND EFFICIENCY WITH EESTRICTED DIET. 



with Dr. H. being 4.8 mg. and the three values found for H. F. being 

 5.6, 4.5, and 2.5 mg. No post-absorptive nitrogen figures are available 

 for Dr. Kellogg. It is clear, however, that Prof. C. was excreting 

 nearly twice as much nitrogen as the other subjects and hence was on a 

 fairly high nitrogen level. The fact that his metabolism per kilogram 

 of body-weight was so low — but 0.2 calorie higher than that of H. F. or 

 19.9 calories as compared with 19.7 calories — must in all probability 

 be due solely to excess body fat. Both subjects were distinctly 

 over-weight and showed low metabolism per kilogram of body- weight. 



It thus appears that a critical examination of the metabolism data 

 for these individuals with supposedly low metaboHsm does not show 

 appreciable deviations from the normal. With a rare pathological 

 case there may be justification for laying weight upon the metabolism 

 of a single individual, but the Nutrition Laboratory has, in recent years, 

 strongly opposed the use of such individual data for comparison. 

 Furthermore we have strenuously objected to an undue use of a so-called 

 "standard" figure for the metabolism, as we believe that individual 

 variations may be so great as to render these individual comparisons 

 practically valueless. Hence, while the evidence for both Mr. Fletcher 

 and Dr. Kellogg, and particularly the latter, did not indicate a notice- 

 ably low metabolism due to dietetic habits, it seemed best to study 

 the question with groups of individuals, since with these only can 

 convincing data be obtained. 



With the idea that a vegetarian diet, which might be assumed to be 

 likewise a low-protein diet, would result in a low metabolism, a series 

 of investigations was carried out with approved technique at the Battle 

 Creek Sanitarium, by Benedict and Roth (Journ. Biol. Chem., 1915, 

 20, p. 231). Through the courtesy of Dr. Kellogg, a large number of 

 men and women vegetarians were thus studied. It became clear to 

 us at this time that the so-called group system of comparison was abso- 

 lutely necessary, namely, that only individuals of like height and weight 

 may properly be compared. Hence for comparison with the men and 

 women vegetarians we selected a group of normals, i. e., non-vegetarians, 

 of like weight and height. The vegetarians, even with a presumably low 

 nitrogen output and a less stimulated plane of metabolism due to the 

 lowered nitrogen metabolism, did not have a lower total metabolism 

 than the individuals subsisting on a mixed diet. 



In an analysis of the results obtained with some 150 individuals^ it 

 was found not only that, strictly speaking, there is no constancy in the 

 basal metabolism, but also that those instances in which the metabo- 

 lism is low give no indication of a general picture of unusually low 

 metabolism due to other than well-known causes. In consideration of 

 the fact that sex, age, muscular training, and body composition {i. e., 

 proportion of inert body-fat and active protoplasmic tissue) , height in 



1 Benedict, Journ. Biol. Chem., 1915, 20, p. 263. 



