10 HAROLD L. HIGGINS 



caloric levels of intake and use ; weather, sex and custom are probably the 

 most important. Women will tend to take less food than men; thus I 

 have found that several Women weighing sixty kg. took about 2,000 Cal- 

 ories per day, while men of the same weight took about 3,000, both doing 

 approximately the same work. In summer we eat less than in winter. 

 Some individuals take large quantities of food (in fact, seem "gluttons"), 

 while others eat much less (have the "appetite of a canary"). 



Carbohydrate and Fat Metabolism 



In fasting, the body calls upon its own tissues to furnish the energy and 

 heat necessary for life. At the beginning of a fast, glycogen, fat and 

 protein are available. The body carbohydrate or glycogen is the most 

 available, for in fasting, as in feeding, the carbohydrate seems to be 

 burned first, in preference to the fat or protein. But the glycogen store 

 is soon depleted, as it amounts to only from fifty to two hundred and fifty 

 grams, according to the amount of carbohydrate eaten previous to the fast 

 (Benedict (&), 1907). With Levanzin in his fast, there was estimated to 

 be a store of approximately two hundred grams, and most of it had been 

 burned in the first three days. Experiments with animals show that some 

 glycogen remains in the tissues for long periods during fasting. It seems 

 likely that this small store is being continually replenished by carbohydrate 

 formed from the body protein. It has been found in experiments with 

 dogs that glycogen does not completely disappear until forty per cent of 

 the body weight has been lost (Michailesco, 1914) ; it is also when the 

 body has lost forty per cent of its weight that death -usually occurs. No 

 glycogen was found in the liver of a dog which had fasted one hundred and 

 four days, dying suddenly at that time (Hawk, 1912). Carbohydrate is 

 also found as glucose in the blood. Sugar persists in the blood throughout 

 fasting. 



After the third day, the body has to rely upon fat and protein for 

 its supply of energy. This leads to the formation of the acetone bodies, 

 acetone, diacetic acid and (5-oxybutyric acid. These substances begin to 

 appear in the urine, breath and blood soon after fasting begins. They are 

 apparently, excreted readily and do not accumulate sufficiently to deplete 

 seriously the alkali reserve of the body. The amount of these substances 

 formed vary with the individual ; the obesity of that person is not neces- 

 sarily the determining factor in the quantity formed. The amount of 

 these substances vary closely with the nitrogen excreted in the urine, i. e., 

 with the protein destruction ; the explanation of this is not exactly clear, 

 but one will recall that in fasting if more glycogen is burned less protein 

 is used, as carbohydrate spares protein. Similar observations have been 

 made in diabetes, for the lowered acetone body, output and acidosis in the 



