A comparative examination of the behavioral aspects of obesity will be undertaken. The control of food intake, with particular attention paid to the detailed analysis of meal patterns, will be studied in ventromedial hypothalamically lesioned rats, genetically obese rats, and rats made obese by hormonal and dietary manipulations. Changes in food intake, body weight, and patterning of feeding will be examined during the development and maintenance of obesity, in response to cold stress, and when constraints are placed on the frequency, size, and duration of meals. The long term effects on food intake and obesity of chronic infusions of insulin and 2-deoxy-d-glucose will also be explored. By comparing different models of obesities simultaneously, these investigations should separate differences in experimental procedures from underlying behavioral mechanisms.