A pilot study to determine what dose of DHEA is needed over an 8 week period to restore physiologic levels of this hormone, suppress markers of bone resorption, and increase markers of bone formation. Underweight patients with eating disorders have been found to have subnormal levels of DHEA, as well as severe osteopenia and/or osteoporosis. These patients have also been found to have both decreased bone formation and increased resorption. The study will examine if subnormal levels of the hormone are related to these bone abnormalities in bone formation and turnover. The investigators seek to obtain safety and efficacy data in this pilot study in order to design a subsequent longitudinal study which will more definitively evaluate the use of DHEA in these disorders.