In the late 20th century obesity became an epidemic. The importance of obesity as a risk factor for a number of conditions, including type 2 diabetes, cardiovascular
disease, hypertension, gallstones and certain cancers, is well documented. Often associated with insensitivity to insulin, obesity is clearly a key factor in the development of the metabolic syndrome – a risk for both diabetes and
cardiovascular disease. In this article, Robert Eckel and Scott Grundy explore the underlying causes of obesity and insensitivity to insulin.