Hơn một nửa của tất cả người lớn Mỹ được phân loại là thừa cân (BMI 25 kg/m2) và một phần ba được coi là béo phì (BMI 30 kg/m2). Tỷ lệ béo phì tăng 50% trong vòng 20 năm qua tại Hoa Kỳ (Yanovski & Yanovski, 1999), nhưng một sự gia tăng tương tự đã được chứng minh trên toàn thế giới. | MEDICAL COMPLICATIONS 183 OBESITY More than half of all US adults are classified as overweight BMI 25 kg m2 and one in three is considered to be obese BMI 30 kg m2 . The rate of obesity has increased by 50 over the past 20 years in the USA Yanovski Yanovski 1999 but a similar increase has been shown world wide. For example the MONICA study and more recent studies in England see Seidell Rissannen 1998 have demonstrated that the percentage of obesity in Europe has also undergone a sharp increase making obesity the most common nutritional disease in industrialised countries. Binge eating disorder BED which is classified as an eating disorder not otherwise specified in the DSM-IV APA 1994 has been described as the most relevant eating disorder for overweight individuals. It has been estimated that approximately 20-30 of overweight persons seeking help at weight loss programmes are classified as binge eaters Spitzer et al. 1993 . This is one of the reasons why mental health professionals need to know about the highly prevalent condition of obesity Devlin et al. 2000 . Excess weight increases the risk of other severe illnesses including hypertension diabetes coronary heart disease CHD and some forms of cancer. Any treatment approach must recognise that obesity is a chronic stigmatised and costly disease. Recently major advances have been made in identifying the components of the homeostatic system which regulate the control of food intake and body weight Schwartz et al. 2000 . The identification of obesity-related genes and hormones as well as the development of new drugs raises hope for the treatment of this serious epidemic. HEALTH RISKS ASSOCIATED WITH OBESITY In clinical practice body fat is most commonly estimated by using the body-mass index BMI kg m2 . A graded classification of overweight and obesity using BMI values provides valuable information about increasing body fatness. A World Health Organisation WHO expert committee has proposed a classification for .
