The global childhood obesity epidemic and the association between socio-economic status and childhood obesity

Abstract

Abstract This paper describes the current prevalence and time trends of childhood obesity worldwide, and the association between childhood obesity and socio-economic status (SES). Childhood obesity has become a global public health crisis. The prevalence is highest in western and industrialized countries, but still low in some developing countries. The prevalence also varies by age and gender. The WHO Americas and eastern Mediterranean regions had higher prevalence of overweight and obesity (30-40%) than the European (20-30%), south-east Asian, western Pacific, and African regions (10-20% in the latter three). A total of 43 million children (35 million in developing countries) were estimated to be overweight or obese; 92 million were at risk of overweight in 2010. The global overweight and obesity prevalence has increased dramatically since 1990, for example in preschool-age children, from approximately 4% in 1990 to 7% in 2010. If this trend continues, the prevalence may reach 9% or 60 million people in 2020. The obesity-SES association varies by gender, age, and country. In general, SES groups with greater access to energy-dense diets (low-SES in industrialized countries and high-SES in developing countries) are at increased risk of being obese than their counterparts.

Figure 1

(A) Worldwide prevalence of obesity in children and adolescents. (B) Worldwide combined prevalence of overweight and obesity in children and adolescents. The prevalence estimates were calculated as the arithmetic mean of the age-specific estimates. Adapted from Epidemiology of Obesity in Children and Adolescents (Pigeot et al., 2011, p. 228, Figure 13.2) with kind permission of Springer Science & Business Media.

Figure 2

Trends in the prevalence (%) of obesity (BMI ≥ 95th percentile) in US children and adolescents by age: 1971–1974 to 2009–2010. Based on national data collected in NHANES (Wang and Beydoun, 2007; Ogden et al., 2012).

Figure 3

Yearly average change in BMI (kg/m²), waist circumference (WC) (cm) and triceps skinfold thickness (TST) (mm) by their percentile distributions in US adolescents: 1988–1994 to 1999–2004. OLS estimate of average yearly shift within percentile groups based on NHANES III (1988–1994) and 1999–2004 data. Adapted from Beydoun & Wang (2010).

Figure 4

Trends in the prevalence (%) of overweight and obesity in Chinese school-age children, by gender: 1985–2005. Based on Chinese BMI cut-off points and data reported by Ji & Cheng (2008).

Figure 5

Association between family affluence and obesity in adolescent boys aged 11, 13 and 15 years from five countries: Example of overweight inequality regression lines. Data were collected from the Health Behavior in School-Aged Children study. Family affluence was measured as a function of family possessions (e.g. car ownership, number of computers, child had own bedroom) and number of family travels over the past year. Adapted by permission of Macmillan Publishers Ltd, International Journal of Obesity (Due et al., 2009, p. 1088, Figure 1).

Figure 6

Time trends in disparities of overweight prevalence by socio-economic status (SES) in US children and adolescents: 1971–1975 to 1999–2002. Obesity was defined as a BMI ≥ 95th percentile. The sample size in each National Health and Nutrition Examination Survey (NHANES) was: NHANES I (n = 6555), NHANES II (n = 6741), NHANES III (n = 9731), and NHANES 1999–2002 (n = 7390). Adapted by permission of the American Society for Nutrition from the American Journal of Clinical Nutrition (Youfa Wang & Qi Zhang, 2006, p. 709, Figure 1). *Significant between-group differences, P < 0.05 (chi-square tests).