Global Trends in BMI Among Children and Adolescents
What are the estimated worldwide trends in mean body mass index (BMI) among children and adolescents?
Data from 2,416 population-based studies with 128.9 million participants ≥5 years of age were included in this analysis. Mean BMIs were calculated for children and adolescents aged 5-19 years. Standard deviations (SDs) were to define children and adolescents as moderately and severely underweight (>2 SD median of the World Health Organization growth reference), mildly underweight (2 SD to <1 SD below the median), overweight (>1 SD to 2 SD above the median), and obese (≥2 SD above the median). Healthy weight was defined as 1 SD below the median to 1 SD above the median).
Of the 128.9 million participants included in this analysis, 31.5 million were age 5-19 years. Regional change in age-standardized mean BMI in girls from 1975 to 2016 ranged from virtually no change (–0.01 kg/m2 per decade; 95% credible interval –0.42 to 0.39, in eastern Europe to an increase of 1.00 kg/m2 per decade (0.69–1.35) in central Latin America and an increase of 0.95 kg/m2 per decade (0.64–1.25) in Polynesia and Micronesia. The range for boys was from a nonsignificant increase of 0.09 kg/m2 per decade (–0.33 to 0.49) in eastern Europe to an increase of 0.77 kg/m2 per decade (0.50–1.06) in Polynesia and Micronesia. Trends in mean BMI have recently flattened in northwestern Europe and the high-income English-speaking and Asia-Pacific regions for both sexes, southwestern Europe for boys, and central and Andean Latin America for girls. By contrast, the rise in BMI has accelerated in east and south Asia for both sexes, and southeast Asia for boys. Global age-standardized prevalence of obesity increased from 0.7% (0.4–1.2) in 1975 to 5.6% (4.8–6.5) in 2016 in girls, and from 0.9% (0.5–1.3) in 1975 to 7.8% (6.7–9.1) in 2016 in boys. The prevalence of moderate and severe underweight decreased from 9.2% (6.0–12.9) in 1975 to 8.4% (6.8–10.1) in 2016 in girls and from 14.8% (10.4–19.5) in 1975 to 12.4% (10.3–14.5) in 2016 in boys. Prevalence of moderate and severe underweight was highest in India, at 22.7% (16.7–29.6) among girls and 30.7% (23.5–38.0) among boys. Prevalence of obesity was >30% in girls in Nauru, the Cook Islands, and Palau; and boys in the Cook Islands, Nauru, Palau, Niue, and American Samoa in 2016. Prevalence of obesity was about 20% or more in several countries in Polynesia and Micronesia, the Middle East and North Africa, the Caribbean, and the United States. In 2016, 75 (44–117) million girls and 117 (70–178) million boys worldwide were moderately or severely underweight. In the same year, 50 (24–89) million girls and 74 (39–125) million boys worldwide were obese.
The investigators concluded that the rising trends in children’s and adolescents’ BMI have plateaued in many high-income countries, albeit at high levels, but have accelerated in parts of Asia, with trends no longer correlated with those of adults.
These data are critical for development of effective health policy and public health programs to reduce both underweight and overweight or obesity among children and adolescents.
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