Seeking overweight men and women between the ages of 25 and 45. The Neuroendocrine Unit at Massachusetts General Hospital is seeking healthy men and women who are 25-45 years old for a research study. We are studying the effects of fasting on body composition, bone density and energy use. The study includes a 12 day in-patient study visit. Participants receive physical examinations, nutritional analyses, hormonal evaluations, blood tests, measurements of bone density and body composition. For more information or to find out if you’re eligible to participate, please contact Pouneh Fazeli, MD at 617-726-1347 or pkfazeli@partners.org