METABOLISM 17 



A patient on the Banting diet, therefore, must inevitably 

 suffer some loss of muscle besides his loss of fat. 



The metabolic balance-sheet above described may be 

 regarded as a standard or average one for a man of 

 medium weight and doing a moderate amount of 

 muscular work. We have now to discuss how it is 

 affected by various external and internal influences. 



1. Influence of Age and Sex. The child, as some- 

 one has remarked, ' is not merely a young city, but a 

 city of young inhabitants.' In other words, owing to 

 their greater youth, the vital activity of the cells is 

 greater in childhood, and metabolism more intense. 

 The demand for food, therefore, apart from the necessity 

 for meeting the requirements of growth, is greater than 

 in the adult. Doubtless, too, the greater metabolic 

 activity of the child explains the immunity of childhood 

 from certain diseases e.g., gout which are common in 

 later life. In old age, on the other hand, respiratory 

 exchange and heat production are found to fall, so that 

 life may be maintained at this period on a very small 

 amount of food. 



Sex appears to exert but little influence upon meta- 

 bolism if allowance be made for differences of weight and 

 build. 



2. The * build' of the body exercises considerable 

 influence upon metabolism. Tall people have a larger 

 surface in proportion to their bulk than short ; their 

 heat loss is therefore greater, and a larger sum of 

 energy in the form of food must be taken in to balance 

 it. This may explain why it is that tall persons are apt 



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