Obesity Epidemiology

DESCRIPTIVE EPIDEMIOLOGY OF OBESITY TRENDS 21distribution of BMI (with a long right tail in adolescents) corresponds to an increase inBMI in adults, indicating increasing prevalence of severe or morbid obesity.International Obesity TrendsThe obesity epidemic first started in the United States and other industrialized nationsbefore spreading to developing countries, especially their urban areas. Data from nationalsurveys in Great Britain show that since 1980, the prevalence of obesity in adults hadalmost tripled, with a similar rise in childhood obesity. 32 The First Israeli National Healthand Nutrition Survey 1999-2001 showed a prevalence of overweight at 39.3% of the adultpopulation, with obesity prevalence at 22.9%. 33 In Turkey, the prevalence of obesity inadults increased from 18.6% in 1990 to 21.9% in 2000. 34 Korea carried out national healthand nutrition surveys of adults and children in 1995, 1998, and 2001 and found substantialincrease in prevalence of obesity over time. The data from 2001 indicated an overallprevalence of adult overweight (BMI ≥ 25 kg/m 2 ) of 30.6% (32.4% in men and 29.4%in women). 35 Between 1992 and 2002, the prevalence of overweight in Chinese adultsincreased from 14.6% to 21.8%. 36 In a cross-sectional survey of a nationally representativesample of 15,540 Chinese adults aged 35 to 74 years in 2000-2001, the age-standardizedprevalence of overweight was 26.9% in men and 31.1% in women. 37 The prevalence ofoverweight was higher in northern than in southern China, and higher in urban thanrural residents. Epidemiologic surveys from other countries including Australia, 38 Japan(National Nutrition Survey), 39 and Malaysia 40 have also found a rapid increase in prevalenceof obesity over the past two decades.Accumulating data notwithstanding, few nations have conducted systematic surveysto assess and monitor obesity trends over a long period of time (e.g., several decades).Katzmarzyk 41 analyzed Canadian population surveys since 1953 to examine seculartrends in stature and BMI over time. Median stature increased 1.4 cm/decade in menand 1.1 cm/decade in women, whereas median body weight increased 1.9 kg/decadein men and 0.8 kg/decade in women. The average weight-for-height increased 5.1% inmen and 4.9% in women. The respective prevalence of overweight (BMI 25-29.9 kg/m 2 )and obesity (BMI ≥ 30 kg/m 2 ) increased from 30.3% and 9.7% in 1970-1972 (basedon measured BMI values) to 35.8% and 14.9% in 1998 (based on self-reported BMIvalues) for men and women, respectively. More recent self-reported data on the adult(≥18 years) population showed a continued increase in the prevalence of overweight andobesity. 42 Data show a shift to the right in the entire distribution of BMI since 1970-1972,particularly in men. This trend is similar to that seen in the U.S. population.Prentice 43 compiled data on the prevalence of obesity across the world and madeseveral observations: (a) very high rates of obesity in several of the Pacific Islands,with record rates in Nauru, where prevalence in some populations approached 80%;(b) generally lower prevalence of obesity in Asian nations, but with rapidly increasingrates in China, India, and other countries, especially in urban areas; (c) a higherprevalence of obesity in North America than in Europe, but with the gap quickly narrowing(more than half of the 15 original members of the European Union had a prevalenceof obesity in excess of 20% in 2002); 44 (d) high prevalence of obesity in manyMiddle Eastern countries, with rates similar to those of the United States in some,such as Bahrain; and (e) generally low prevalence of obesity in Africa, but with greatheterogeneity (for instance, Ghana has a 3% prevalence of obesity compared with 21%in South Africa).