BASAL METABOLISM. 



59 



value originally established at the end of the fifth day of fasting, for 

 it is apparent that although the body requirement was only about 

 1,600 calories, the ingestion of food having a fuel value of about 2,000 

 calories was not sufficient to raise the metabolism to the initial level 

 of the first two fasting days, i. e., 1,800 calories. In this, as in all 

 other experiments, strict attention was paid to the necessity of securing 

 comparable conditions of muscular activity. Such variations as were 

 unquestionably present have been carefully discussed in detail in a 

 previous publication. 1 The data there given show that the energy of 

 the estimated muscular activity was extraordinarily constant through- 

 out the 5 days of fasting and the 3 days with food; the difference can 

 not therefore be explained by differences in muscular activity. 



Still another series of experiments was made with this subject 

 March 4 to 14, 1905, in which the fasting experiment continued for 

 7 days and the food experiment 3 days. 2 The diet in the food experi- 

 ment consisted of milk, gluten crackers, an apple, orange juice, and a 

 small quantity of a breakfast food. As shown in table 10, the average 

 value for the heat production for the first 2 days was 1,767 calories. 



TABLE 10. S. A. B., March 4-14, 1905. (24-hour periods, 7 a. m. to 7 a. m.) 



Mixed diet (per day): 



Amount, 1,274 grams; nitrogen, 6.45 grams; total energy, 1,841 calories. 

 Fuel value, 1,788 calories; from protein, 9 per cent; from fat, 37 per cent; from 

 carbohydrates, 54 per cent. 



After the ingestion of the mixed diet, which had a fuel value of 1,788 

 calories, the metabolism returned to the level of the first 2 days, but 

 was not raised above it. It was, however, about 200 calories higher 

 than the metabolism on the seventh day of the fast. Thereafter the 

 metabolism remained essentially constant, the progressive increment 



Benedict, Carnegie Inst. Wash. Pub. No. 77, 1907, p. 486, table 234. 



2 For the detailed results of this experiment, see Benedict, Carnegie Inst. Wash. Pub. No. 77, 1907, 

 experiments Nos. 75 and 76. 



