Normal dexamethasone suppression in obese binge and nonbinge eaters with rapid weight loss

Natural or experimental starvation is frequently associated with hypercortisolism, reflected as incomplete suppression of serum cortisol after dexamethasone. To determine whether rapid weight loss per se or some other aspect of starvation induces disruption of the hypothalamic-pituitary-adrenal (HPA) axis, we evaluated 2 categories of obese women (body mass index > 30 kg/m2) undergoing rapid weight loss: binge eaters (n = 12) and nonbinge eaters (n = 8). We performed psychometric evaluation and 1 mg overnight dexamethasone suppression tests in the obese subjects, as well as in 12 race- and age-matched normal-weight women. The obese women were tested before and after 12 weeks of a 3349 kJ/day (800 kcal/day) liquid formula diet, and lost an average of 19.3 kg, which represented 17.3% of their total body weight. Binge eaters, who were initially more depressed than either nonbinge eaters or normal-weight controls, had a significant amelioration of their symptoms with weight loss. Neither group had evidence of disruption of the HPA axis before or after weight loss. Thus, the rate of failure to suppress cortisol after dexamethasone was approximately 10% in each of the obese and control groups, and did not differ between the pre- and postweight loss condition or between binge eaters and nonbinge eaters. Serum free T4 was unchanged, whereas T3 fell significantly with weight loss. We conclude that weight loss may improve affect in the obese without altering HPA axis activity, and postulate that one of the concomitants of restricted energy intake, perhaps in combination with a threshold body weight, may be of greater importance in causing abnormalities of dexamethasone suppression testing than rapid weight loss per se.