American Journal of Clinical Nutrition, Vol 27, 1065-1070, Copyright © 1974 by The American Society for Clinical Nutrition, Inc.

Differential effects of diet composition and weight loss on glucose tolerance in obese women

¹ From the Department of Nutritional Sciences, University of California, Berkeley, California, U.S.A.

Oral glucose tolerance tests were performed on obese subjects during a period of stable weight and again during weight reduction. The subjects subsisted on liquid formula diets of varying compositions. When the subjects were at their customary weights, oral glucose tolerance "improved" when isocaloric diets contained more carbohydrate and less protein. During the subsequent weight reduction program this "improvement" was maintained despite a considerable reduction in carbohydrate and calorie content of the diet. Fasting serum insulin concentration and serum insulin response with respect to changes in serum glucose levels were not significantly elevated when compared with those of nonobese controls. Fasting growth hormone concentrations were not significantly elevated. During the 3 hours following oral glucose administration, serum growth hormone levels tended to fall irrespective of the diet. These findings suggest that changes in diet composition and weight loss both contributed independently to the improved carbohydrate tolerance of these obese subjects.