Reprinted from the Proceedings of the NATIONAL ACADEMY OF SCIENCES, 

 Vol. 4, pp. 370-373, December, 1918 



A BIOMETRIC STUDY OF HUMAN BASAL METABOLISM 



BY J. ARTHUR HARRIS AND FRANCIS G. BENEDICT 



NUTRITION LABORATORY AND STATION FOR EXPERIMENTAL EVOLUTION, 

 CARNEGIE INSTITUTION OF WASHINGTON 



Communicated October 8, 1918 



Investigators are now generally agreed that the metabolism, expressed in 

 terms of calories per uriit of time, of the normal subject shall be taken as a 

 basis of comparison in the investigation of all the special problems of human 

 nutrition, for example, that of the requirements for muscular activity, that of 

 the influence of specific diseases or of the level of nutrition upon metabolism, 

 that of the change of metabolic activity with age, and so forth. Critical in 

 vestigations in both European and American laboratories have shown that the 

 gaseous metabolism is so affected by various factors that determinations which 

 are to serve as a standard must be made under very exactly controlled condi 

 tions. It is not merely necessary to devise apparatus in which the physical 

 difficulties of direct calorimetry (or of the exact measurement of gaseous ex 

 change from which heat production may be computed) are overcome. Cer 

 tain biological factors must be ruled out. Those of greatest importance as 

 sources of experimental error are muscular activity and the stimulatory ac 

 tion of recently ingested food. The heat production of the individual in a 

 state of complete muscular repose 12-14 hours after the last meal, i.e., i . the 

 postabsorptive condition, has been called the basal metabolism. 



For a decade the Nutrition Laboratory has been engaged in carrying out a 

 series of determinations of basal metabolism in normal human individuals of 

 both sexes and of widely different ages. These have been made with all the 

 modern refinements of method and manipulation. The subjects were in pre 

 sumably good health. All those with febrile temperature were discarded. 

 All were in the postabsorptive condition. Perfect muscular repose during the 

 short periods required for indirect calorimetry was assured by an automatic 

 record of all movements, even those imperceptible to a trained observer. 



370 



