530 ENERGY EXCHANGE AFTER FOOD 



cannot be any doubt but that an important part of the in- 

 crease in gas metabolism after intake of food should be 

 assigned to this account. But a number of authors, as 

 C. Voit, Eubner, Magnus-Levy, Jaquet and others are op- 

 posed to special emphasis of this factor. Important doubts 

 have been raised as to whether the special rise in metabolism 

 after protein feeding, which Eubner has spoken of as the 

 specific dynamic effect of the protein, is to be explained 

 entirely by the digestion work. 32 



Specific-dynamic Effect of Proteins. It is to be under- 

 stood that the idea of a specific-dynamic action of proteins 

 is not in the least antagonistic to the "law of is o dynamics.'' 

 In accordance with the latter the different food materials 

 may in the matter of heat production be mutually inter- 

 changed according to the full value of their physiological 

 availabilities and take part in the production of heat with 

 their full energy values; but according to Eubner 's idea 

 particularly in case of the proteins a greater part of the 

 energy is lost by change into heat for the activities of the 

 cellular life as such. 



As heat production within the body of the warm-blooded 

 animal has to do with compensating for the loss of heat in 

 the body surface, Eubner is of the opinion that the specific- 

 dynamic influence of foods can be seen in the clearest pos- 

 sible relation by excluding the surface heat loss by providing 

 a temperature equal to that of the body in the surrounding 

 medium. He therefore kept a dog at 33 C., first determined 

 the minimal metabolism in fasting, and then gave for a time 

 a diet made up of proteins, or of fats, or carbohydrates, with 

 the same caloric equivalent as the fasting requirement, and 

 observed the production of heat. Increase of heat produc- 

 tion was observed, for sugar, 5.8 per cent. ; for fat, 12.7 per 

 cent., but for proteins, 30.9 per cent. A protein diet with 

 the same caloric value as the hunger-requirement is in- 



82 Cf. Literature concerning the specific dynamic action and the work of 

 digestion; L. B. Mendel, Ergebn. d. Physiol., 11, 457-460, 1911. 



