92 METABOLISM IN SEVERE DIABETES. 



body and oxygen consumed. The loss in insensible perspiration is, then, not 

 simply an evaporation of water from the body, but consists, in part at least, of 

 an actual loss of organized body-tissue that has been oxidized by the oxygen 

 taken into the lungs and given off both as carbon dioxide and as water result- 

 ing from the oxidation of organic hydrogen. 



Referring again to curves I and II in fig. 1, it will be seen that the increase 

 in weight found after taking food was due simply to the weight of the food 

 taken into the intestinal tract, and that the noticeable losses in weight follow- 

 ing the passage of urine and feces were due to the loss of these materials from 

 the body. In discussing changes in body-weight, the important point to note 

 is whether there are additions to or losses from the total body-mass, the inci- 

 dental fluctuations due to the taking on of food or the passage of urine or feces 

 being of no great importance. If, then, during a period of one year, the body 

 gradually increases in weight a number of pounds or loses a number of pounds, 

 it is clear that these changes in weight can not be due to minor fluctuations in 

 the quantity of water or food taken, of urine passed, or of feces excreted. 



A factor which should be taken into consideration in interpreting changes 

 in body-weight is the fluctuation in the water-content of the body. Under 

 certain conditions it is possible for the body to retain considerable quantities of 

 water and, indeed, to be deprived of considerable amounts of water that would 

 normally be retained. Since about 60 per cent of the body is water, any 

 change of water-content may result in material gains or losses in body-weight. 

 A man weighing, for example, 65 kilos, may have an absolute water-content of 

 40 kilos., so that a relatively small change in the percentage of water in the 

 body may produce a change in body-weight of 1 kilo. 



It was observed many years ago by Bischoff and Voit, 1 in a series of experi- 

 ments with animals, that when the diet was in large part carbohydrate there 

 was a tendency for the body to retain water in that the muscular tissues became 

 more moist. By means of the respiration calorimeter at Wesleyan University, 

 Middletown, Connecticut, an interesting experiment was made on a man 

 which showed conclusively the effect of the constituents of a diet on the water- 

 content of the body. 2 During the experiment, which lasted 6 days, the sub- 

 ject was confined inside of a respiration chamber and spent 8 hours of the day 

 riding a stationary bicycle ergometer, thereby doing a considerable amount of 

 muscular work. The daily routine and the quantity of work performed were 

 adjusted so that they would be the same on all days. During the first three 

 days the subject was given a diet containing a large amount of carbohydrate, 

 the total diet being nearly, although not quite, sufficient to supply him with 

 energy for the amount of work he was to do. In this period, which was pre- 

 ceded by a preliminary period with the same diet, the body retained its weight 

 for a number of days. On the fourth day the character of the diet was materi- 

 ally altered by decreasing the carbohydrate and increasing the fat. Singularly 

 enough, although the actual total weight of food ingested was somewhat more 



'Bischoff und Voit, Die Gesetze der Erniihrung des Fleischfrcssers, Leipsic, 1860. 

 'Benedict and Milner, U. S. Dept, Agr., Office Exp. Stas. Bui. 175, 1907, p. 225. 



