Research/Areas of Interest: Etiology of obesity and its complications; the role of inflammation in metabolic disorders and the regulation of adipocyte metabolism, inulin resistance, and diabetes He studies obesity, regulation of fat cell metabolism, insulin resistance, and systemic regulation. Dr. Greenberg is noted for discovering the protein perilipin and the concept of intracellular lipid droplets as well as the role of perilipin in white and brown fat metabolism. He and his collaborators demonstrated that fat tissue and fat cells secrete cytokines—substances that have direct effects on other cells—and also that estrogen increases energy expenditure in mice in several ways. Dr. Greenberg is a physician in the Department of Endocrinology, Diabetes, and Metabolism at Tufts Medical Center, Robert C. and Veronica Atkins Professor of Nutrition and Metabolism at Tufts University School of Medicine, Associate Professor in the Friedman School of Nutrition Science and Policy, and Associate Director of Boston Nutrition Obesity Research Center. He is board certified in Internal Medicine as well as Endocrinology and Metabolism. He is a member of the American Diabetes Association, American Society of Biochemistry and Molecular Biology, American Society for Nutrition, Endocrine Society, and The Obesity Society.