Abstract
Obesity is a major risk factor for a number of diseases. It has direct effects on glucose and lipid metabolism and on blood pressure, leading via these to type 2 diabetes, coronary heart disease and cerebrovascular disease. These comorbidities are particularly associated with excess intra‐abdominal fat. Other important diseases which obesity increases the risks of include obstructive sleep apnoea, osteoarthritis of weight‐bearing joints and a number of types of cancer. In addition to these medical comorbidities obesity has many adverse social and psychological costs. Copyright © 2001 John Wiley & Sons, Ltd.