STABVATIl 



the starvation amounl plus all thai we have given id; and although 



by daily giving this amounl of protein there maj be a Blight decline 

 1 lie excretion, it will never come near to being the Bame as that of tin- 

 intake The only effed of Buch feeding will be t<> prolong [if e p,,. a 



few days. 



Nitrogenous Equilibrium. To attain equilibrium we must . 

 amounl of protein whose nitrogen eontenl is at Least two and one-half 

 times thai of the starvation level. For a few -lays following the estab- 

 lishment of this pure protein diet, the nitrogen excretion will be far in 

 excess of iIk' intake, bu1 it will gradually decline until tin- tun practically 

 correspond. Eaving once gained an equilibrium, we may raise In 

 level by gradually increasing the protein intake During this prog 

 sive raising of the ingested protein, it will be found, at least in the c 

 nivora cat and dog), thai a certain amounl of nitrogen is retained by 

 the body for a day or so immediately following each increase in p 

 t.-in intake. The excretion of nitrogen, in other words, does nol immedi- 

 ately follow the dietetic increase. 'I 'he amounl of nitrogen thus retaine* 

 too greal to be accounted as a retention of disintegration products 

 protein; it must therefore be due to an actual building up of new | 

 tein tissue — that is. growth of muscli 



Nitrogenous equilibrium on a protein diet alone is readily attainable 

 in the <-at, ami less readily in the dog. Bu1 in man ami tin- herbivor 

 animals, it is impossible to give a sufficiency of protein alone to maintain 

 equilibrium; there will always he an excess of excretion over intake. 

 Indeed it scarcely requires any experiment to prove this, for it is sol f- 



evident when we consider that there are less than 1 » <* in a pound of 



uncooked lean meat, and thai there are few who could eat over tl 

 pounds a day, an amount, however, which would scarcely furnish all of 

 the required calorics. A person fed exclusively on flesh is the 

 being partly starved, even although he may think thai he is eating 

 abundantly and be quite comfortable and active. This fad 

 tical application in the so-called Banting i In. 



Protein Sparer*. Very different results are obtained when (hy- 



drates or fats are freely given with the protein to the starving anii 

 Nitrogen equilibrium can then be regained on very much 

 so thai we speak of fats and carbohydrates as being ". 

 Carbohydrates are much better protein sparers than 

 are so cfiicieiit in this regard that it is now common!) believed 

 bohydrates arc essential for life, ami that when I us no 



trace of carbohydrates, a part of the carbon of p 

 verted into carbohydrate. This important truth is su| 

 dence derived from other fields of investignti 



