Obesity in men and women.

The prevalence of obesity in the UK, defined as a Body Mass Index (BMI) exceeding 30, is increasing. Obese people with BMI greater than 30 have a much greater risk of dying earlier than people with desirable levels of fatness (as do extremely lean people with BMI less than 20). The relationship between obesity and the likelihood of suffering certain metabolic diseases such as coronary heart disease, stroke and diabetes is now thought to be associated as much with the distribution of the excess fat as with the amount of excess fat. Fat distribution is usually measured in the population by the waist to hip circumference ratio (WHR). A high WHR seems to be a proxy measurement for an excess of intra-abdominal fat. Subcutaneous fat mass can be estimated using skinfold measurements. Exact determinations can only be performed directly using expensive equipment, such as computed tomography (CT). People with high WHR measurements can be said to have a 'central' fat distribution: people with low WHR measurements can be said to have a 'peripheral' fat distribution. 'Central' fat distribution carries most metabolic risks and is associated with a predisposition towards coronary heart disease, stroke, diabetes, breast cancer and gallstones. In some cases, the distribution of fat is a stronger risk factor than total obesity. 'Peripheral' fat distribution carries least metabolic risk. However, risks related to the mechanical problems of carrying excess fat, such as varicose veins, are increased. The risks of obesity therefore depend on the distribution of fat as well as total fatness.(ABSTRACT TRUNCATED AT 250 WORDS)