Changes in Body-Weight. Ill 



diet contained about 750 grams of solid matter and sufficient water to make 

 the total weight of the materials ingested equal 3860 grams on the first day 

 and 4900 grams on each of the other 2 days, the average for the 3 days being 

 4550 grams per day. Although the total weight of food and drink ingested 

 during the fat period was somewhat greater than during the carbohydrate pe- 

 riod, there was actually a very marked loss to the body, averaging 914 grams 

 per day, as determined by the balance with which the subject was weighed. 

 The computations of the gains and losses of protein, fat, carbohydrate, water, 

 and ash showed an average daily loss of 974 grams. That this loss in weight 

 was in large part water is shown by an examination of the data, by whicli it 

 is seen that during the fat period there was an average loss from the body of 

 12 grams of protein, 47 grams of fat, 2.5 grams of carbohydrate, 906 grams of 

 water, and 7 grams of ash per day. Even on the third day of the period the 

 results show a loss of some 800 fframs of water. 



o 



Although there are differences between the balance as found by means of the 

 actual weights of the subject and that calculated from the materials gained 

 or lost, it is reasonable to suppose from a careful inspection of the analytical 

 data, that the losses in weight as computed from the gains and losses of material 

 are somewhat more accurate than those obtained from the weights of the man. 

 The apparatus then in use for weighing the man, while satisfactory for long 

 experiments, has since been much improved, as its accuracy was by no means 

 all that could be desired in studying such a problem as this. Fortunately, we 

 have the direct chemical data indicating the katabolism of the protein, fat, 

 carbohydrates, water, and ash. 



The total energy furnished by both diets was substantially the same and the 

 amount of external work performed was identical in both experiments. The 

 heat eliminated by the body was on the average 70 calories larger in the experi- 

 ment with the fat diet. It is significant that during the 6 days with the two 

 diets, the body sustained a continuous loss of energy approximating 500 calories 

 per day, and that during the 3 days with the carbohydrate diet the subject 

 gained on the average about 60 grams per day. 



Value of further study of diet as influencing the store of water. Further 

 experiments are much needed to study the influence of varying diets upon the 

 store of preformed water in the body. Such experiments would be of practical 

 value in studying the effects of the ingestion of salt, mineral metabolism, and 

 the gains or losses of weight noted in pathological cases. This influence of 

 diet is of particular importance in cases of dropsy. What factor determines 

 the retention of water and what factor determines the loss of water is certainly 

 of great importance, and more experiments on this point should be made. It 

 is apparent, therefore, that but little reliance can be placed upon fluctuations 

 in body-weight in experiments of short duration, if such marked changes can 

 occur during a period of 6 days, when muscular activity, energy of diet, and 

 protein ingestion remain constant, and variations occur only in the relative 



