The Hypothalamic-Pituitary-Adrenal (HPA) Axis as an Effector System in Weight Regulation

Inclusion Criteria: * Subjects with complete adrenal failure as defined as spontaneous serum cortisol of levels less than 5 g/dl after 12 hours without glucocorticoid replacement and peak serum cortisol of \< 5 g/dl 60 minutes after a 250 g ACTH stimulation test. * Subjects who are at their usual weight (weight stable for at least 1 year) * Subjects on stable replacement doses of any required hormone such as thyroid, sex hormones, mineralocorticoid replacement, growth hormone, and hydrocortisone for at least 6 months, and 4) have a normal body weight (BMI 19-27 kg/m2). Exclusion Criteria: * Possible confounders on body weight and insulin resistance * Age less than 18 to exclude those who might be experiencing alterations in cortisol production or weight as a result of adolescent growth. * Subjects who exercise \> 30 minutes/day, 3 times a week. * Smokers. * Heavy alcohol drinkers (\> 2 drinks/ day). * Subjects with medical diagnosis including diabetes, heart disease, and cancer. * Subjects with psychiatric illness (i.e., depression, psychosis, bipolar, schizophrenia; or are taking medications for these disorders).