Influence of weight reduction on carbohydrate and fat metabolism and on serum insulin response in obesitySummary. To find out which of the metabolic changes observed in obesity are reversible by a reducing diet, we examined 37 obese out-patients with a mean overweight of 71~o B~ocA. A manifest diabetes mellitus and endocrine diseases were excluded by clinical means. 20 subjects showed disturbances of carbohydrate-tolerance. Oral and i.v. glucose-tolerance tests gave normal results in 17. Both subgroups were put on a 1000 cal. mixed diet and had mean weightdosses of 21.2, vs. 17.5 kg, corresponding to 34% vs. 28% BROCA, i.e. less than half of their overweight. --The following changes were observed in the subgroup with impaired carbohydrate-tolerance: --1. Significant improvement of glucose-tolerance with beginning normalization of fasting blood sugar, 120' value after oral glucose and of the k-values for i.v. and oral glucose-tolerance tests. --2. Highly significant reduction of the elevated fasting values for free serum glycerol with normalization of the quotient: free fatty acids/glycerol in fasting serum. --3. Significant fall of the high levels for insulin-like activity and for immunologically reacting insulin. --Under identical conditions the subgroup with normal carbohydrate-tolerance showed only a moderate increase of free fatty acids 90' and 120' after glucose. In the obese group as a whole, we found a reduction of serum esterified fatty acids under low calorie diet. --The changes described under 1--3 were more pronounced with this dietary treatment than in fasting periods generally described until now, and occurred predominantly in the subgroup with impaired carbohydrate-tolerance. Our findings indicate that hyperinsulinism held responsible for obesity up to now by some authors is probably adaptire.

Oral (o.GTT) and intravenous glucose * Fiir die Unterstiitzung bei der Durchffihrung dieser Untersuehungen sind wir der Deutsehen Forschungsgemeinsehaft zu Dank verpfliehtet.