This proposal attempts to study the hypothesis that in morbidly obese men, blockade of type II glucocorticoid receptors by mifepristone will lead to sustained appetite suppression and increased thermogenesis with resulting spontaneous weight loss. Females have been excluded in this pilot study due to the known abortifacient and teratogenic properties of this drug and the potential risk in the event of birth control failure since hormonal means of birth control would interfere with the study.