We have reason to believe that not only the different sugars but also the different amounts of sugars vary somewhat in regard to the actual height to which the metabolism may be increased and the time when the maximum metabolism appears. It is important, therefore, to determine as accurately as possible both of these factors. In the calorimeter experiments it was found that the maximum heat production occurred some time during the first or second hour. Since in the respiration experiments observations are made every 15 or 20 minutes, it is possible to determine with considerable accuracy when the maximum or "peak" effect of carbohydrate ingestion appears. This is shown for the carbon-dioxide excretion, oxygen consumption, and heat production for all of the respiration experiments in tables 169 to 172.

Dextrose

Ten experiments were made with 100 grains of dextrose with 9 subjects and four experiments with 75 grains of dextrose with two subjects. The greatest percentage increments are shown in table 169. In the experiments with 100 grams of dextrose the carbon-dioxide maximum increments show very large values. Thus, in no experiment was the maximum increment in the carbon-dioxide production less than 12 per cent, while in one case it rose as high as 35 per cent, the average being 25 per cent. The average time at which the maximum values occurred was 1 1/2 to 1 3/4 hours after food. The oxygen consumption shows maxima with wide degrees of divergence, these ranging from 3 to 22 per cent, with an average for the 10 experiments of 12 per cent. The average time when this maximum appeared was between 1 and 1 1/4 hours after food. The heat production varied from 6 to 24 per cent above the basal value, the average being 14 per cent. Like the carbon-dioxide production, this maximum increment occurred on the average between 1 1/2 and 1 3/4 hours after food. We thus have a fairly consistent picture with 100 grams of dextrose of an average maximum increase of 25 per cent in the carbon-dioxide production, 12 per cent in the oxygen consumption, and 14 per cent in the heat production, with an average time after food for the appearance of the maximum of 1 1/2 to 1 3/4 hours.

Table 169. - Maximum Effect Of Ingestion Of Dextrose On Carbon Dioxide, Oxygen, And Heat In Respiration Experiments

1Period from the time when subject finished eating to the end of the last observation, except in cases when the increment of heat ended earlier. See tables 126 to 139 for complete observations.

2Sugar taken with juice of one lemon on this day.

3Sugar taken with juice of one-half lemon on this day.

4Same value occurs 1 1/4 to 1 1/2 and 13/4 to 2 hours after food.

5In cereal coffee (about 300 c.c. solution).

6Same value occurs 2 to 2 1/4 hours after food.

In the 75-gram experiments the average of the maximum increment values for the carbon-dioxide production was 19 per cent and for the oxygen consumption was 12 per cent. The average of the maximum values for the heat production was 13 per cent, this being but slightly less than that found with 100 grams. Basing our conclusions upon these four experiments, therefore, the reduction in the amount of carbohydrate ingested from 100 to 75 grams produces but a relatively slight decrease in the maximum effect. The time at which this occurred was not greatly different from that in the 10 experiments with 100 grams of dextrose, being from 1 1/4 to l 1/2 hours.

Thus, with dextrose, the results obtained with the respiration apparatus completely confirm the observations with the respiration calorimeter that the maximum effect with carbohydrates is obtained inside of the first 1 or 2 hours. The average length of the observations, i. e., from the taking of the food to the end of the last experimental period, was 4 hours with 100 grams and 2h50m with the 75-gram amounts. It is clear that in both series of experiments the observation was sufficiently long to include the possible maximum effect.

Levulose

With 100 grams of levulose 7 experiments were made with as many different subjects. (See table 170.) The carbon-dioxide production showed even greater maximum increments than in the case of the dextrose, namely, from 25 per cent to 38 per cent, with an average of 32 per cent. The maximum increment in the oxygen consumption ranged from 8 per cent to 14 per cent, with an average of 11 per cent. The "peak" effect in the heat production ranged from 11 per cent above basal to 18 per cent, with an average of 15 per cent. The experiments continued for an average length of 4h40m, the greatest exception being that with A. J. O., which was but lh29m. On the average the maximum effect was obtained between 1 1/4 and 1 1/2 hours after the taking of food. Two experiments with but 75 grams, both with J. J. C, showed maximum values strikingly uniform with those obtained on the average with the 100-gram amount. Since there was but one subject, however, the comparison has no great value, particularly as no 100-gram experiment was made with this subject. Although the second experiment with J. J. C. was only lh45m in length, it is probable that the maximum effect occurred in this time.

Sucrose

Eight experiments with 100 grams sucrose and seven experiments with approximately 75 grams sucrose give a fairly good picture of the maximum effect due to the ingestion of sucrose. The data are shown in table 171. In the last three experiments with 100 grams the length of the observation was not so great as in the experiments previously considered, and in one or two instances the experiment was probably terminated before the effect had ceased. As the time at which the maximum effect occurred agrees fairly well with that in the other experiments, these short experiments are included in table 171. With 100 grams of sucrose the carbon-dioxide increments were exceptionally large, ranging from 38 to 58 per cent, with an average of 47 per cent. With the oxygen consumption, the maximum increment ranged from 15 per cent to 27 per cent with an average of 20 per cent. The maximum increase in heat production ranged from 19 to 31 per cent with an average of 24 per cent. The highest increment occurred on the average from 45 to 60 minutes after the ingestion of the sugar.