<qa>  What is the weight loss period?Subjects will be admitted to the Rockefeller University Hospital for the 10 week in-patient phase of the study. The first 2 weeks consist of a weight stabilization period, during which subjects will be required to eat an average American diet. This is followed by the 6 week weight loss period where subjects will be put on a low calorie high fatprotein diet. During the weight loss period, calories will be cut by 50 compared to the weight stabilization period. This will be followed by a 2 week weight maintenance period during which calories will be added to the diet to maintain the new weight. Appropriate adjustments will be made to keep the subjects weight stable. 