104 
PHYSIOLOGY: BENEDICT AND EMMES 
A COMPARISON OF THE BASAL METABOLISM OF NORMAL 
MEN AND WOMEN 
By Francis G. Benedict and L. E. Emmes 
NUTRITION LABORATORY. CARNEGIE INSTITUTION OF WASHINGTON 
Presented to the Academy, January 13, 1915 
From the earKest attempts to adjust food intake to the energy re- 
quirement it has been recognized that the dietetic needs of men as a class 
are somewhat greater than those of women. This increase has been 
commonly ascribed in large part to the variations in the muscular ac- 
tivity and yet there has been a definite belief that the basal energy 
requirement for women may be materially different from that for men. 
In connection with observations made on a large number of normal 
men and women, primarily for the purpose of comparing them with 
pathological subjects, we have accumulated the results of observations 
on 89 men and 68 women, all of whom were in 'presumably good 
health.' The experiments were made with essentially the same tech- 
nique and with the subject in the same condition of muscular repose and 
the post-absorptive state, i.e., 12 hours after the last meal. Under 
these conditions, differences due to muscular activity are entirely elimi- 
nated and we obtain the basal normal caloric output of the individuals 
studied. 
The total heat production, computed on the 24-hour basis, was greater 
with the men, i.e., 1638 calories as against 1355 calories with the women. 
Of special interest is the fact that the oxygen consimiption per kilogram 
per minute — a imit of measurement comtmonly employed by physiolo- 
gists — -was remarkably uniform with both sexes, being 3.65 cc. with the 
men and 3.58 cc. with the women. On the basis of heat-production 
per 24 hours, the men showed 25.5 calories per kilogram of body weight 
and the women 24.9 calories. On the debatable unit of apportion- 
ment of heat-production per square meter of body surface the men had 
832 calories per 24 hours against 772 calories for the women. 
It should be borne in mind, however, that the 89 men had an aver- 
age body-weight, without clothing, of 64.3 kg. and the 68 women a 
body- weight of but 54.5 kg.; furthermore, the average height of the 
men was 172 cm. and that of the women 162 cm. A direct, unqualified 
comparison of the total metaboKsm of these two classes, or of the metab- 
ohsm per kilogram of body weight or per square meter of body surface 
is, therefore, not permissible for it is not logical to compare two groups 
of individuals with unlike weight and height. 
