154 GENERAL METABOLISM 



the true basal metabolism. In practice the most complete 

 rest attainable involves considerable activity of the heart 

 and lungs. The minimum of activity which can be attained 

 occurs when the body is at complete mental and physical 

 rest, when no digestion or absorption of food is going on, 

 and when loss of heat by radiation is at its minimum. 

 This is usually taken as the Basal or Standard Metabolism. 

 It has been estimated as 1 Calorie per kilogramme of body 

 weight per hour, or about 1700 C. per diem, for a man of 

 average weight and size. In different individuals it varies, 

 not with the weight but with the area of body-surface. 



The energy output of an average person doing sedentary 

 work has been found by direct and indirect calorimetry 

 to be about 2500 C. per diem. AVhen hard manual work 

 is performed this figure may be doubled. These results 

 agree fairly well with the energy intake as estimated 

 statistically from the amount of food supplied to large 

 communities. From the figures thus obtained it appears 

 that the average daily consumption of food corresponds 

 in men to an intake of 2500 C. for sedentary workers, 

 and 4000 C. for those employed in manual labour. 



