METABOLISM DURING STARVATION 



675 



Days 



1-3 

 4-5 



6-8 



Average daily out- 

 put of nitrogen 



. 1-67 grm. . 

 . 1-46 . 

 3-21 



Average amount of 

 fat oxidised daily 



10-3 grm. 

 . 10-3 

 24 , 



We see therefore that during starvation, apart from the first day or two, 

 the animal derives the main portion of its necessary energy from the com- 

 bustion of fats, provided that there is a sufficient store of these substances in 

 the body. A certain consumption of protein is unavoidable. Since protein 

 comes from the working tissues of the body they are spared so far as possible, 

 and it is only when the stored fat is used up that any large call is made on 

 the tissue protein. * 



BASAL METABOLISM 



During starvation the energy output of the body furnished by the con- 

 sumption of its own tissues is determined (a) by the amount necessary to 

 keep the body alive i. e. to maintain its warmth and to furnish the energy 

 for respiratory movements, contractions, of the heart, etc. ; (b) the energy 

 necessary to carry out any work that is performed. 



The energy requirements under (a) represent the ' Basal Metabolism ' 

 of the body. We have already seen that this varies with the weight of the 

 individual ; but if a number of different animals are compared, their meta- 

 bolism per kilo is found to be greater the smaller the animal, as is shown 

 in the following table : 



This is due to the fact that the chief expenditure of energy is devoted to 

 maintaining the temperature of the body, and the smaller the animal the 

 larger is its surface and therewith its heat loss relatively to its weight. The 

 basal metabolism therefore is a function of the surface of the body, 

 and in the above table a comparison of metabolism per square metre body 

 surface shows that it is practically the same in all cases. As shown in the 

 following Table, we may say that a warm-blooded animal requires a daily 

 expenditure of about 1000 Calories per square metre body surface in order 

 to maintain its temperature and carry out filch motor processes as are 

 essential to life. 



