$38 PRACTICAL ORGANIC AND BIO-CHEMISTRY 



A man of the average weight of 70 kilos, performing light muscular 

 work under starvation conditions loses 2240 large calories a day. 

 To counterbalance this loss and making allowances for the non-utilisa- 

 tion in the body of some of the food, a diet yielding from 2500-2700 

 calories is required. The standards usually adopted are those of 

 Atwater, namely : 



3000 calories for light muscular work 

 3500 ,, medium 



4500 heavy ,, 



The main part of the caloric value of the food is supplied by the 

 carbohydrate and* fat of the diet. The quantities of these food-stuffs 

 are increased or diminished so as to produce the necessary caloric 

 value, whilst the daily supply of protein is varied very slightly ; 

 no gm., 125 gm., 150 gm. for light, medium, and heavy work 

 respectively. Although smaller quantities of protein, from 60-70 

 gm. as shown by Chittenden and by Hindhede, can be taken without 

 loss of body weight and with perfect maintenance of health, yet the 

 figure of 90-100 gm. of protein is regarded as a daily minimum. 



In considering protein as a diet, reference should be made to the 

 relative amounts of the constituent amino acids. A protein diet 

 should contain all the amino acids ; if an amino acid be absent in a 

 protein it should be eaten as such or given in another protein. 

 A diet consisting of 



500 gm. carbohydrate will give a caloric value of 2050 



60 fat 558 



100 ,, protein ,,410 



Total 3018 



These figures represent dry weight. The actual content of protein, 

 carbohydrate and fat in various food-stuffs is given on p. 537. 



If we make a 10 per cent, allowance for non-utilisation, the 

 caloric value becomes 2700. 



The average daily output in the urine of the various nitrogenous 

 constituents on a fixed carbohydrate and fat diet, but variable protein 

 diet (egg-white, meat, etc.), the total quantity ingested corresponding 

 to 100 gm. standard is given in the following table: 



