Dr. Leibel's research focuses on the genetics of obesity and noninsulin-dependent diabetes. His laboratory has mapped, cloned, and identified mutations in the obese and fatty genes in rats, mice, and, more recently, in humans. The obese gene encodes leptin, an adipose derived hormone responsible for regulating body weight, whereas the fatty gene encodes the leptin receptor. Currently, his research group is defining the physiological bases by which this and related signaling networks regulate body size and composition. For example, changes in leptin production following reduction in body fat might play a role in the metabolic changes that accompany weight loss in humans. Dr. Leibel's laboratory is also working to isolate additional rodent genes that influence body weight and the susceptibility to noninsulin-dependent diabetes mellitus in the context of obesity. Laboratory members have extended their genetic studies to search for similar obesity and diabetes-related genes in human families.