<qa>  What is the last month of the study dedicated to a transition from liquid diet to solid foodTo participate in this study, subjects have to stay at the Rockefeller University Hospital as inpatients for about two months and continue the study as outpatients for 4 more months. During the outpatient period, subjects have to attend a clinic visit once a week. During the first 3 weeks of the study, subjects are introduced to a weight stabilization liquid diet. During this time, the initial weight is maintained and baseline study tests are performed. When testing is completed, a very low calorie liquid diet and leptin or placebo administration are initiated. Weight is monitored until 10 weight loss is achieved. At this time, a second testing period is performed in an inpatient setting. When testing is completed, weight loss and leptin or placebo treatment continue at home in an outpatient setting until 20 weight loss is achieved. When this period is completed, a third testing period is performed in an inpatient setting. The last month of the study is dedicated to a transition from the liquid diet to solid food, and to weight maintenance education provided by the hospital staff in an outpatient setting. A solid food weight maintenance diet is provided to participants during this period. At the end of this period, two days of testing are performed and leptinplacebo administration is discontinued. 