800 NUTRITION AND HEAT REGULATION. 



body of another of the same weight be all consumed. The oxidizing 

 capacity of the body differs in different individuals and some will 

 lay on fat more readily than others, because for them an excess 

 of material is provided by a relatively small diet. Fundamental 

 differences of this character in the properties of the protoplasm are 

 frequently transmitted by heredity through many generations. 

 Those individuals who show little tendency to lay on fat may 

 be made to do so by largely increasing the amount of food, or more 

 certainly by altering the mode of life. A sedentary life, absence 

 of worry, etc., may lead to a tendency of this kind, while a very 

 active muscular life has the opposite effect. Men who lead a very 

 muscular life farmers, fishermen, etc. are rarely disposed to ac- 

 cumulate fat to a noticeable degree. So also the use of alcoholic 

 beverages may indirectly favor accumulation of fat, presumably by 

 depressing the oxidizing capacity of the tissues. The tendency to 

 form fat may exhibit itself in some cases to such an extent as to con- 

 stitute an almost pathological condition. Extreme obesity may be 

 counteracted by altering the mode of life, especially by . taking 

 much muscular exercise, or more directly by dieting. The diet for 

 such purposes should be reduced in amount, and should be as free as 

 possible from fats and carbohydrates, consisting of such material 

 as eggs, fish, lean meat, salads, fruits, etc. The well-known 

 Banting diet, devised by a London physician (1864) for the cure 

 of obesity, makes use of this latter principle.* 



Summary of the General Functions of Fat. The general 

 functions fulfilled by the fats may be summarized briefly under 

 the following heads: (1) It provides a store of reserve food which 

 is used by the body in case of deficiency of food or complete starva- 

 tion. The fattening of hibernating animals before their winter 

 sleep and the humps of the camel give conspicuous examples of this 

 peculiarity. (2) By its oxidation in the body it furnishes a part 

 of the heat energy necessary to maintain the body temperature. 

 On account of its high combustion equivalent (1 gm. of fat yields 

 9.3 Calories) fat is very effective in this respect. Inhabitants 

 of cold regions choose a diet rich in fat. (3) It is a proteid-saver. 

 Like the carbohydrate food, its oxidation protects the proteid from 

 consumption. In starvation, therefore, the amount of proteid 

 destroyed daily is smaller as long as any fat remains, and, under 

 ordinary conditions of life the larger the amount of fat in the diet, 

 the less the amount of proteid necessary for maintaining the body 

 in nitrogen equilibrium. Experiments show that in this respect 

 the fat is not so effective as an equivalent amount of carbohydrate 

 food. The difference is referable probably to the greater difficulty 

 of oxidation of the fatty material. 



* For practical directions concerning the treatment of obesity by dieting 

 see Gautier, " L'alimentation et les regimes." Paris, 1904. 



