INGESTION OF CARBOHYDRATES. 195 



The conclusion, then, may fairly be drawn that the ingestion of 

 carbohydrate material has a pronounced and continuous effect upon 

 the carbon-dioxide production, which may last 8 hours or more, and 

 increases the oxygen consumption for a short time, generally a little 

 over 2 hours. The respiratory quotient also shows a marked rise. 

 The increase in the oxygen consumption is paralleled by a definite 

 increase in the heat production. The last observation is of the greatest 

 significance in connection with calorimeter experiments, as it demon- 

 strates by direct calorimetry a positive increase in the heat production 

 as the result of the ingestion of varying amounts of carbohydrates. 



MAXIMUM EFFECT OF CARBOHYDRATE INGESTION ON METABOLISM 



(DIRECT CALORIMETRY). 



To what extent the basal heat production may be increased as a 

 result of carbohydrate ingestion may best be shown by considering 

 the data in table 123. In this table the results are grouped according 

 to the carbohydrates studied. The amounts ingested, the total length 

 of observation, and the maximum increase above the basal value are 

 here recorded. The length of time between the taking of the food and 

 the maximum increase is also noted. 



Unfortunately the calorimeter experiments are not sufficiently num- 

 erous, either as to the number of experiments with each carbohydrate 

 or the number with the same amounts of food, to permit satisfac- 

 tory Comparisons of the relation of the individual carbohydrates to 

 the maximum heat production. It is much to be regretted, also, 

 that more experiments with pure carbohydrates were not made instead 

 of with such mixed carbohydrates as bananas, popcorn, and rice. 

 At the time these studies were made, however, the main purpose was 

 to determine the possible maximum effect of carbohydrate ingestion 

 upon the basal heat production. This is clearly established, as will 

 be seen from the results given in the table. Although, with the pos- 

 sible exception of bananas and sugar, the evidence is not sufficiently 

 complete to allow deductions as to the differences between the indi- 

 vidual carbohydrates, the general picture is tolerably clear. 



With sucrose it will be seen that the largest amount of heat was pro- 

 duced when the largest amount was ingested. This occurred in the 

 experiment with A. H. M. on April 1, 1907, in which the period of 

 experimenting was 8 hours, subdivided into four 2-hour periods. In 

 this experiment an increment of 17 per cent was found in the period 

 from j to 2| hours after food. A smaller amount of sugar taken by 

 F. M. M. on January 31, 1910, produced an increment of but 11 per 

 cent within one hour of taking the sugar, while a still smaller amount 

 with A. W. W. produced an increase of 8 per cent in approximately 

 the same time. In all cases the maximum increment was found from 

 ^ to 2\ hours or even less after the ingestion of the carbohydrate. 



