The specific dynamic effects of carbohydrate, fat and protein were measured in five adult women. Basal metabolic rates were measured while subjects were in the post-absorptive state. Subjects ingested 5.7 Cal./kg of body weight of the nutrients on different days. Measurements were made at regular time intervals after the meal until the amount of expired air approximated that of the basal state. Samples of expired air were analyzed for oxygen and carbon dioxide. Changes in the respiratory quotient and Cal. per square meter of body surface, with relationship to time of ingestion of each pure compound were studied.

There was a general trend for subjects with higher basal energy metabolism to have greater increases in the respiratory quotient after the ingestion of carbohydrate, or fat or protein. An increase in respiratory quotient and beat production was observed following the ingestion of each of three nutrients. There was no definite correlation between the changes in respiratory quotient and variations in heat production after ingestion of carbohydrate, fat and protein by women. Individuals varied in their responses to carbohydrate, fat and protein, but similarities among the individuals in their response to each of these foodstuff was apparent.