World Health Organization

Obesity and overweight are defined as an accumulation of excess body fat, to an extent that may impair health. A crude population measure of excess fat is the body mass index (BMI), a person's weight (in kilograms) divided by the square of his or her height (in meters). WHO defines overweight as a BMI of 25 or more, and obesity as a BMI of 30 or more. These cut-off points can provide a reference for individual assessment.

There is also evidence that, on a population level, the risk of chronic disease increases progressively as average BMI increases above 21. A high body mass index is a major risk factor for a number of chronic diseases, including cardiovascular diseases, cancer and diabetes.

[Page 816]

[Page 817]

[Page 818]

[Page 819]

[Page 820]

[Page 821]

[Page 822]

[Page 823]

[Page 824]

[Page 825]

[Page 826]

[Page 827]