Is cortisol involved in upper-body obesity?

Abstract

Obesity is a major health problem that can be defined as an excess of body fat, associated with hypertension, diabetes and coronary heart disease. Several groups have evaluated the clinical significance of variations in fat cell distribution on these complications. A frequently used index of fat cell distribution is the waist to hips ratio ( W H ). A high W H ratio is said to reflect upper body fat cell distribution while a low waist to hips ratio reflects a lower body type fat cell distribution. Studies have shown that those whose W H ratio indicate upper body fat cell distribution had a higher prevalence of diabetes and hypertension than those with the lower type. Over the years cortisol has attracted considerable interest as a possible factor in the development and maintenance of obesity. The clinical findings associated with upper body type of obesity are in many ways similar to those of the hypercortisol state. Our hypothesis is that upper body obesity forms a unique subgroups of the obese population and their regional fat distribution is associated with mild cortisol excess. In humans, studies have reported that some obese subjects hypersecrete cortisol and have an increase in the cortisol production rate. Although recent studies would tend to discount any influence of cortisol in human obesity, several factors should be taken into consideration. It is difficult to measure cortisol economy in obese subjects because among other things the measurements are less than precise; and cortisol secretion changes during the day and in response to outside stimuli. Further, obesity is a heterogeneous disorder and not all obese subjects may have the same disorder. Studies showing no difference in cortisol economy have frequently excluded diabetic and hypertensive subjects, most of which exhibit the upper body type of fat cell distribution. By exclusion of these subjects previous studies may have missed a most interesting subgroup and selected toward a study population which does not have upper body obesity. As yet there are no studies which compare the cortisol economy of obese patients who have upper body obesity to those who have lower body obesity. This study should be done not only over a 24 hr. period, but in response to specific stimuli (like meals) since a hormonal abnormality may not necessarily be present at all times.