Can We Slow Down the Global Increase of Adiposity?

Excess bodyweight is a major public health concern increasing worldwide with substantial variation between nations. Between 1980 and 2008, mean body mass index (BMI) increased by 0.4 kg/m² per decade for men and by 0.5 kg/m² for women. In 2008, an estimated 1.46 billion adults worldwide had BMI of 25 kg/m² or greater.

Among the high-income countries, United States had the highest BMI.¹ Recent birth cohorts are becoming obese in greater proportions for a given age, and are experiencing a greater duration of obesity over their lifetime.² Global prevalence of childhood adiposity increased dramatically since 1990 starting already in preschool children. In 2010, 43 million children (35 million in developing countries) were estimated to be overweight or obese. The worldwide prevalence increased from 4.2% in 1990 to 6.7% in 2010 and is expected to increase to 9.1% in 2020.³ In the semi-rural community Bogalusa (Louisiana), childhood obesity epidemic has not plateaued and the proportion of overweight/obese 5 to 17 years old youths even increased from 5.6% in 1973/1974 to 30.8% in 2008/2009.⁴

Because adiposity is associated with cardio-metabolic risk factors, even in young children, and higher BMI during children is associated with an increased risk of coronary heart disease (CHD) in adulthood, successful prevention of adiposity in youth could reduce cardiovascular disease (CVD) in adults.^5–8 An elevated BMI in adolescence constitutes a substantial risk factor for obesity-related disorders in midlife. Elevated BMI in both adolescence and adulthood were independently associated with angiography- proven CHD.⁹ Effective treatment of obese individuals can substantially reduce risk factors for CVD and improve disease management.¹⁰

The stable or decreasing trends in central and Eastern Europe for women between 1980 and 2008¹ indicate that we may slow down the increase of adiposity. However, the intrinsic inter-play among eating patterns, physical activity, and sedentary behavior limits implementation of simple recommendations. This is complicated further by overlap of genetic and environmental factors. Nevertheless, the American Heart association highlighted evidence-based experience for population-wide approaches to obesity prevention.¹¹ In the first place, it is preferable to avoid the excess weight gain that leads to over-weight and then obesity.

The need for treatment is highest among low-income and ethnic minority populations who have a high burden of obesity but less access to health services. Ethnic disparities in obesity prevalence apply to both BMI and Waist circumference (WC). For example, the clinical consequences of obesity are higher for Asian descent at lower BMI and WC cut points than for whites. Thus a WHO report suggested that overweight in adults should be defined as a BMI of 23 kg/m² instead of generally used 25 kg/m² and a more recent article called for revisions of BMI criteria for South Asians, Chinese, and Aboriginals.¹² Ethnic disparities in BMI and WC, such as defining the components of the metabolic syndrome, are also observed in male and female children and adolescents.¹⁴,¹⁵ Therefore, nationality specific percentile curves are mandatory. Examples for children and adolescents are given.¹⁶,¹⁷

Arresting development of obesity in childhood has the greatest long-term payoff in years of healthy life.¹¹ The United States preventive Services Task Force recommends comprehensive moderate– to high-intensity programs that include dietary, physical activity, and behavioral conunseling components.¹⁸ The Task Force found adequate evidence that multi-component, moderate- to high-intensity behavioral interventions for obese children and adolescents can effectively yield short-term (up to 12 months) improvements in weight status. Inadequate evidence was found regarding the effectiveness of low-intensity interventions. Family-based programs for overweight/obese children might be a promising approach for long-term weight reduction in moderately obese children who maintained body weight for two years by teaching parents only.¹⁹ Among 3 programs, the parent-centered dietary modification approach was more successful than the child-centered physical activity program or both.²⁰

In the USA the prevalence of high BMI for age among children and adolescents did not increase significantly between 2003 and 2006. This might be a positive signal that we can slow down the increase of adiposity if we intensify global efforts following the recommendation of McCarthy²¹ to aim at a waist-to-height ratio of 0.5 disregarding age and gender.