Differential stimulation of cortisol and dehydroepiandrosterone levels by food in obese and normal subjects: relation to body fat distribution.

Abstract

It has been previously shown that food intake elevates circulating ACTH and cortisol levels, but no report has been published regarding the changes in circulating dehydroepiandrosterone (DHEA). DHEA was originally described as a weak androgen, but more recently it has been associated with a wide range of metabolic functions. In addition, previous studies have described a hyper-responsive hypothalamo-pituitary-adrenal axis in obese subjects in response to various stimuli, but the specific response to food has not been studied. We studied the effect of food on the hypothalamo-pituitary-adrenal axis in 20 subjects of normal body mass index (BMI range 18-25) and also in a group of 12 obese subjects (BMI range 34-61). Levels of glucose, insulin, ACTH, cortisol and dehydroepiandrosterone were measured every 20 minutes. A small rise in DHEA accompanies the rise in circulating ACTH and cortisol in response to food in both lean and obese subjects, but DHEA rose independently of cortisol and ACTH on the fasting day. In the obese subjects, food induced a significantly greater change in serum cortisol (peak cortisol rise (mean +/- SEM); normal-weight group, 169 +/- 14%; obese group, 294 +/- 23%) and in the cortisol/DHEA ratio (area under the curve; normal-weight group, 202 +/- 15%; obese group, 292 +/- 29%) than in the normal-weight subjects. This difference was particularly notable in those with central-type obesity (waist/hip ratio > 0.80). A group of the normal, jean female subjects showed no cortisol rise after food intake. Our results suggest that DHEA may vary independently of circulating cortisol, and that the cortisol response to food is enhanced in obese subjects, particularly in those with central obesity. We speculate that there may be a caused connection between the cortisol response to food in normal subjects, and the subsequent distribution of fat if such subjects overeat sufficiently to become obese.