This paper was delivered at the 23-25 October 1997 conference _T he Determination, Treatment, and Prevention of Obesity, which was sponsored by the Institute of Nutrition, University of North Carolina at Chapel Hill; Department of Nutrition, School of Public Health and School of Medicine, University of North Carolina at Chapel Hill; and School of Medicine, East Carolina University, in cooperation with the North American Association for the Study of Obesity, the National Institutes of Health, the American Cancer Society, and Eli Lilly & Company.Defining obesity: an adventure in cardiovascular disease epidemiology - A quantitative analysis of combined information from existing studies

While the association of overweight and health, as well as longevity, has been scrutinized in volumes of research, the association of overweight with cardiovascular disease is a dominant theme in the medical literature. This report will detail the arguments and present selected summaries of published reports that support the emerging consensus that overweight and obesity have the major causal role in the ongoing epidemic of cardiovascular disease in the United States. Examples will include relative risk and attributable risk estimates for several metabolic perturbations caused by overweight, including type 2 diabetes mellitus and hypertension. Results of the Nurses Health Study, which found a fivefold increased risk of type 2 diabetes among women with body mass index between 24.0 and 24.9 compared to the referent group with body mass index =<22, will be highlighted. The presentation will also explicitly identify the position of excess adiposity in the causal chain that leads from overnutrition to the majority of cardiovascular disease. Based on the position in the causal sequence, a strategy for defining the threshold of _o verweight will be described. From the foregoing, it is concluded that the overweight threshold should be no higher than body mass index =25. Finally, it is concluded that the majority of men and women with a body mass index between 22 and 25 are overweight and should be identified and appropriately counseled to improve nutrition and increase physical activity.