Dr. Havel is investigating the regulation of energy homeostasis and carbohydrate/lipid metabolism, and the involvement of endocrine systems in the pathophysiology of obesity, diabetes, and cardiovascular disease. His laboratory is studying the mechanisms regulating the secretion of pancreatic and gastrointestinal hormones and the production of the adipocyte hormones, including leptin and adiponectin. Biochemical and molecular studies are conducted using in vitro systems and the role of endocrine, metabolic, and dietary factors in regulating energy balance, insulin action, and lipid/carbohydrate metabolism is examined in vivo in animals and humans. A major focus of the research is the interaction of diet composition (such as dietary fat and fructose) with the endocrine regulation of energy balance in the development and progression of obesity, diabetes, and dyslipidemia/atherosclerosis, including studies in animal models and clinical studies in humans. His research team is conducting studies on the prevention and treament of diabetes in a new rat model of type 2 diabetes developed in his laboratory. Dr. Havel and his collaborators are also investigating the effects of bariatric surgery procedures on gastrointestinal, pancreatic and adipocyte hormones and how these endocrine changes are involved in the improvements of carbohydrate and lipid metabolism observed after bariatiric surgery.