426 



BIOLOGICAL ENERGETICS 



size and age there is a normal rate of basal metabolism, and any marked 

 deviations therefrom indicate an abnormal, perhaps diseased, condition. 

 Brody has emphasized the relation between the body size and basal 

 metabolism of a large number of animal species. He found that the 

 formula 



Cal. per day = 70 X (body weight in kg.)"-'^^ 



holds very well for a tremendous range of body sizes (Fig. 16-2). Note 

 that the smallest animals have the highest basal metabolism per kilogram 



0.1 1.0 10 



cal. /day i ' ' '""i — ■ ■ ■ '"i-i — ■ > i 



& 



cal./kg./day 

 10.000 



I- Cal. = 39.5 1b.""" 



B.T.U. = 156.8 lb.""* 

 : Cal. = 70.5kg.''"* 



s 



■^ 1,000 



o 



XI 

 (A 



<u 

 ^. 



1 100 



10 



Body Weight, lbs. 



100 1,000 10,000 



'";;;, B.T.U./day 



100,000 



Rabbits 

 Ducks 



Guinea 

 Pigeons 

 Canaries 



Elephants -C^'^ 



Horses-. ^fe 



Dairy bulls 

 Beef cows 

 Beef steers "^^^^ Beef steers 

 Ponies -tr<i^^ Dairy cows 

 Humans -j^^ ^ Swine 



Sheep 

 Dogs 

 20% deviation lines 

 Domestic fowl 



10,000 



-. 1,000 



100 



20 



a 



CO 



"o 



JO 

 oj 



<A 



0.01 0.1 1.0 10 100 1,000 5,000 



Body Weight, kgs. 

 From Brody, Bioenergetics and Growth, Reinhold Publishing Corporation. 

 Fig. 16-2. Relation of body weight to basal metabolism of mature ani- 

 mals of various species. Tlie rising curve, showing basal metabolism per 

 animal per day, is represented very well by the equation, Cal. per day = 

 70.5 X (body weight in kg.) °'"*. However, from the nature of the data the 

 numerical values 0.734 and 70.5 are somewhat doubtful and probably should 

 be rounded off to 0.73 and 70, respectively. The declining curve, showing 

 metabolism per kg. of body weight per day, similarly corresponds to the 

 equation, Cal. per kg. body weight = 70.5 X (body weight in kg.)""-"". 



of body weight, although the largest animals, of course, have the highest 

 total metabolism. More detailed formulas have been worked out for 

 human beings, which take account of age, sex, height, and body surface 

 area, as well as weight. For example, a 30 year old man who is 175 cm. 

 (5 ft. 9 in.) tall and weighs 70 kg. (156 lb.) should have a basal metabolic 

 rate (BMR) close to 1630 Cal. per day.^ 



Total Energy Requirements of Human Beings. The amount of food 



^Calculated from Harris and Benedict's formula (see Sherman, Chemistry of Food 

 and Nutrition, 7th ed., p. 164). 



