Prevalence of obesity

Over recent years, rates of overweight and obesity have escalated rapidly in many parts of the world to epidemic proportions, reflecting increased consumption of energy dense diets high in fats and sugars, compounded by declining levels of physical activity. More than 1.1 billion people are estimated to be overweight, of whom around 320 million are now calculated to be obese. The International Obesity Task Force (IOTF) estimates that up to 1.7 billion people may be exposed to weight-related health risks, taking into account varied Asian populations with a body mass index (BMI) of 23 or more. More than 2.5 million deaths each year are attributed to higher BMI, a figure that is expected to double by 2030.

Regional trends

Average BMI levels across Africa and Asia have been estimated at between 20-23 kg/m2, but in Europe and North America mean levels are much higher at 25-27 kg/m2, indicating that a substantial part of the population may be exposed to the health risks of higher BMIs1IOTF analysis of data gathered for the WHO Global Burden of Disease 2003..

Africa
Wide disparities in levels of obesity are found in this region with the highest rates in South Africa, where mean BMI values for men and women are 22.9 kg/m2 and 27.1 kg/m2 respectively, but levels of central obesity among women have been assessed at 42%2Puoane T, Steyn K, Bradshaw D, Laubscher R, Fourie J, Lambert V, Mbananga N. Obesity in South Africa: the South African demographic and health survey. Obesity Research 2002; 10:1038-1048.. The South Africa Health Review 2000 indicated obesity rates from 8% among black men to 20% among white men, but among women the rates range from 20% for Indian/Asians to 30.5% for black women. In parts of sub-Saharan Africa obesity often exists alongside under-nutrition3Maire B, Delpeuch F, Cornu A, Tchibindat F, Simondon F, Massamba JP, Salem G, Chevassus-Agnes S. Urbanization and nutritional transition in sub-saharan Africa: exemplified by Congo and Senegal. Rev Epidemiol Santé Publique 1992; 40:252-258 (article in French)..

Eastern Mediterranean and Middle East 
High levels of overweight and obesity exist particularly among women, in countries as diverse as Egypt and the Gulf states including Saudi Arabia. Obesity rates of 25-30% and even higher are not untypical in Kuwait, the United Arab Emirates and Bahrain. In Iran, obesity rates vary from rural to urban populations rising to 30% among women in Tehran.  In northern Africa the prevalence of obesity among women is high. Half of all women are overweight (BMI>25) with rates of 50.9% in Tunisia and 51.3% in Morocco, and obesity rates (BMI>30) in women of 23% in Tunisia and 18% in Morocco, representing a three-fold increase over 20 years4Mokhtar N, Elati J, Chabir R, Bour A, Elkari K, Schlossman NP, Caballero B, Aguenaou H. Diet culture and obesity in northern Africa. J Nutrition 2001; 131:887S-892S..

Europe
Few countries in the European Region report obesity rates below 10%. Prevalence rates, particularly among women, rise to more than 20% in countries such as the United Kingdom, Germany, Finland and Greece. The most rapid increase is noted in England where obesity rates have risen three-fold from 1980 to 2001, with levels of morbid obesity (BMI>40) also increasing three-fold among men and almost doubling among women during the 1990s5Department of Health 2001. Health Survey for England. www.doh.gov.uk/..

North America
In the United States obesity affects one in three adults overall, more than double the rate of 20 years ago. Ethnic minorities, particularly women, are even more adversely affected with 40% of Mexican American women and 50% of black American women having a BMI above 30 kg/m2 compared to 30.6% of white women. Extreme obesity rates, classified as morbid or very severe obesity of BMI>40, are as high as 15% among black American women6NHANES 1999-2000. www.cdc.gov/.. Neighbouring Canada experienced an increase of 150% in its overall adult obesity rate from 1985 to 1998 reaching 14.8%, but 40% of men and 25% of women fell into the pre-obese category7Katzmarzky PT. The Canadian obesity epidemic, 1985-1998. CMAJ 2002; 166(8):1039-1040..

In the Caribbean, obesity is a significant problem, particularly among women, with correspondingly high rates of type 2 diabetes. Abdominal obesity, using WHO waist circumference limits, ranged from 3% of men in St Lucia to 8% in Barbados, but among women was found to be as high as 34% in Jamaica, 41% in St Lucia and 45% in Barbados8Okosun IS, Forrester TE, Rotimi CN, Osotimehin BO, Muna WF, Cooper RS. Abdominal adiposity in six populations of West African descent: prevalence and population attributable fraction of hypertension. Obes Res 1999; 7:453-462.. Diabetes studies in Jamaica have demonstrated markedly high risks associated with overweight and central obesity9Wilks R, Rotimi C, Bennett F, McFarlane-Anderson N, Kaufman JS, Anderson SG, Cooper RS, Cruickshank JK, Forrester T. Diabetes in the Caribbean: results of a population survey from Spanish Town, Jamaica. Diabetic Medicine 1999; 16:875-883.. 

South and Central America
Evidence of the impact of the 'nutrition transition' is clear in the growing levels of obesity throughout this region. Obesity rates are reported to vary for men from 7% in Peru and Brazil to more than 20% in Paraguay, where the rates in women rise to as high as 36%10 Filozof C, Gonzales C, Sereday M, Mazza C, Braguinsky J. Obesity prevalence and trends in Latin American countries. Obesity Reviews 2001; 2:99-196..

Western Pacific
Various Asian populations may be particularly susceptible to the health risks of central obesity, regardless of BMI11James WPT, Chunming C, Inoue S. Appropriate Asian body mass indices? Obesity Reviews 2002; 3:139.. Consequently there is an increasing focus on measuring waist circumferences, which can predict individual risk more accurately than body mass index12 Lean ME, Han TS, Deurenberg P. Body composition by densitometry from simple anthropometric measurements. Am J Clinical Nutrition 1996; 63:4-14..

However, Japanese experts have agreed independently to redefine the criteria for obesity as a disease, with a cut-off at BMI>25. Using this standard, adult obesity in Japan would average 20%, rising to 30% in men over 30 years old and women over 40 years old, representing a three to four-fold increase over the last 40 years13The Examination Committee of Criteria for 'Obesity Disease' in Japan, Japan Society for the Study of Obesity. New Criteria for 'Obesity Disease' in Japan. Circulation Journal 2002; 66(11):987-992.  14Kanazawa M, Yoshiike N, Osaka T, Numba Y, Zimmet P, Inoue S. Criteria and classification of obesity in Japan and Asia-Oceania. Asia Pac J Clin Nutr 2002 Dec; 11 Suppl 8:S732-S737.. China has adopted its own standards defining overweight at a BMI of 24 or more, and obesity a BMI of 28 or more, while  abdominal obesity is defined by a waist circumference of 85 cm in men and 80 cm in women15Zhou BF, Cooperative Meta-Analysis Group of the Working group on Obesity in China. Predictive values of body mass index and waist circumference for risk factors of certain related diseases in Chinese adults - study on optimal cut-off points of body mass index and waist circumference in Chinese adults. Biomed Environ Sci 2002; 15:83-95..

The link between obesity and type 2 diabetes is most manifest in the Pacific area which has some of the highest levels of adult obesity. Obesity prevalence rates of between 60% and 80% can be found among men and women in some islands including Samoa and Nauru. In Tonga, 60% of the adult population are obese and recently 12% of men and nearly 18% of women were identified with type 2 diabetes, a doubling of the rate over 25 years. A further 20% were found to be at risk due to elevated blood sugar levels16Colagiuri S, Colagiuri R, Na'ati S, Muimuiheata S, Hussain Z, Palu T. The prevalence of diabetes in the kingdom of Tonga. Diabetes Care 2002; 25:1378-1383..

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