<qa>  What is the name of the study that is administered by leptin or placebo?In this study, leptin or placebo is administered by an injection under the skin, in a way that is similar to injections of insulin to diabetic patients. 50 of the subjects participating in the study are treated by leptin and 50 are treated by placebo. Blood leptin levels are maintained in the pre-diet range in leptin treated subjects by leptin treatment. Subjects treated by placebo will also lose weight if they adhere to the liquid diet provided by the Rockefeller University Bio-nutrition Department. The investigators and the participants dont know if leptin or placebo are used since this is a double blind study. 