1056 ABSORPTION 



that the waste of tissue-proteins proceeds as before. To illustrate, 

 if a dog of medium size excretes on the fifth day of starvation about 

 5 grm. of nitrogen, this loss corresponds to a combustion of 31.25 grm. 

 of protein. Now, if the latter amount be given to this animal as 

 food, it will excrete nearly 10 grm. of nitrogen-waste. In order to 

 cause this animal not to lose more nitrogen than it receives, or better, 

 in order to place it in nitrogen-equilibrium, it is necessary to give it an 

 amount of protein the nitrogen-content of which is at least two and 

 one-half times that of the starvation standard. This same conclusion 

 may be arrived at by a consideration of the data derived from profes- 

 sional fasters. Since the total output of energy, say, on the fifth day 

 of the period of starvation, amounts to 1979 calories and the output of 

 nitrogen to 11.44 grm., it requires 71.5 grm. of protein to meet this loss. 

 But 71.5 grm. of protein yield only 293 calories and hence, the afore- 

 said amount of energy cannot be derived entirely from this protein. 

 The balance must be supplied by the tissue-fat and glycogen. Conse- 

 quently, the loss in the substance of the body cannot be stopped by 

 balancing the output of nitrogen by an equal ingestion of proteins. 

 While it is quite simple to retain by this means the nitrogen-equi- 

 librium in the strictly carnivorous animals, it cannot be kept in this 

 way by the herbivora and omnivora. 



Since man belongs to the latter class and requires about 3000 

 calories for his daily work, it will be seen that at least 3 Ibs. of lean 

 meat must be ingested by him in order to supply this amount of heat, 

 1 Ib. of meat yielding less than 1000 calories. But this method of 

 furnishing the necessary energy for the body soon overtaxes the organs 

 of metabolism and places the person in the condition of partial starva- 

 tion. These facts form the basis of Banting's cure 1 for obesity which, 

 by the ingestion of lean meat, attempts to give the feeling of satisfac- 

 tion connected with a "square" meal, and at the same time causes 

 the body to burn up its reserve materials, retaining as far as possible 

 its proteins. 



If the starving animal is fed a mixed diet instead of pure protein, 

 it is able to retain its nitrogen-equilibrium with much less difficulty, 

 because the ingestion of the proteins can then be made to approximate 

 the waste. The carbohydrates and fats are protein sparers. This is 

 true especially of the carbohydrates, because it has been shown that the 

 combustion of proteins during starvation may be greatly reduced by the 

 ingestion of this foodstuff. Thus, the administration of a large meal of 

 carbohydrates to a starving animal may raise its respiratory exchange 

 20 to 30 per cent. Furthermore, it is possible by this means to reduce 

 the daily output of nitrogen in men who partake of an average diet 

 of from 15 grm. to 6 grm. and less, without causing them to lose their 

 nitrogen-equilibrium. The amount of carbohydrate ingested must, of 

 course, balance the normal daily expenditure of energy. This subject 

 may also be approached the other way, i.e., by determining the amount 



1 Advocated by Wm. Banting, an undertaker of London, 1797-1878. 



