October 11, 2017
4 min read

Childhood obesity increased 10-fold worldwide since 1975

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The prevalence of childhood obesity rates has risen more than 10-fold worldwide during the past 4 decades, with the greatest increases observed in parts of Asia, according to findings reported in The Lancet.

From 1975 to 2016, the number of girls with obesity increased from 5 million to 50 million and from 6 million to 74 million for boys. Despite the rise, more children and adolescents worldwide are moderately or severely underweight than obese, the researchers noted. However, if post-2000 BMI trends continue, childhood obesity is expected to surpass moderate and severe underweight by 2022.

“While average BMI among children and adolescents has recently plateaued in Europe and North America, this is not an excuse for complacency, as more than 1 in 5 young people in the USA and 1 in 10 in the U.K. are obese,” James Bentham, PhD, of the University of Kent, United Kingdom, said in a press release. “Additionally, rates of child and adolescent obesity are accelerating in the east, south and southeast Asia, and continue to increase in other low- and middle-income regions.”

Bentham and colleagues in the NCD Risk Factor Collaboration, a network of health scientists providing data on major risk factors for noncommunicable diseases worldwide, pooled and analyzed 2,416 population-based studies that measured height and weight in 128.9 million people aged at least 5 years to estimate trends from 1975 to 2016 in both mean BMI and BMI categories in 200 countries and territories. Among the included studies, 1,099 sources included data on 24.1 million participants aged 5 to 17 years and 848 sources included data on 7.4 million participants aged 18 to 19 years, with the remaining including data on adults. Most studies (76%) were from 1995 and later. Researchers used a Bayesian hierarchical model to estimate trends from 1975 to 2016 for mean BMI and for prevalence of BMI in the following categories for children and adolescents aged 5 to 19 years: more than 2 standard deviation (SD) below the median of the WHO growth reference for children and adolescents (defined as moderate and severe underweight), 2 SD to more than 1 SD below the median (defined as mild underweight), 1 SD below the median to 1 SD above the median (healthy weight), more than 1 SD to 2 SD above the median (overweight but not obese), and more than 2 SD above the median (obesity). Countries were organized into 21 regions, mostly based on geography and national income, except for Australia, Canada, Ireland, New Zealand, the U.K. and the U.S., grouped as one region due to similar trends in BMI and cardiometabolic risk factors.

Researchers found that, from 1976 to 2016, age-standardized mean BMI increased globally and in most regions. The global increase was 0.32 kg/m² per decade for girls (95% CI, 0.23-0.41) and 0.4 kg/m² per decade for boys (95% CI, 0.3-0.5).

Regionally and between sexes, BMI changes for children and adolescents varied. In Eastern Europe, for example, researchers observed no change during the study period (–0.01 kg/m² per decade; 95% CI, –0.42 to 0.39) in girls to an increase of 1 kg/m² per decade (95% CI, 0.69-1.35) among girls in Latin America. In boys, BMI changes ranged from 0.09 kg/m² per decade in Eastern Europe to 0.77 kg/m² per decade (95% CI, 0.5-1.06) in Polynesia and Micronesia.

In 2016, the lowest mean child and adolescent BMI levels were in South Asia and East Africa, with age-standardized mean BMI between 16.9 kg/m² and 17.9 kg/m² for girls and boys, whereas the highest BMI levels were observed in Polynesia and Micronesia in boys and girls, where age-standardized BMI levels were more than 20 kg/m².

In 4 decades, global age-standardized prevalence of obesity in children and adolescents increased from 0.7% to 5.6% in girls and from 0.9% to 7.8% in boys.

“Obesity increased in every region, with proportional rise being the smallest in high-income regions (on average, 30%-50% per decade) and largest in southern Africa (about 400% per decade, albeit from very low levels),” the researchers wrote.

In commentary accompanying the study, William H. Dietz, MD, PhD, director of the Sumner M. Redstone Global Center for Prevention and Wellness at the Milken Institute of Public Health at George Washington University, said the findings show that a “double burden of nutritional disease” now exists in many regions of the world, such as the Middle East and North Africa, both now dealing with obesity and undernutrition in children.

“Findings of the study provide grounds for both optimism and concern,” Dietz wrote. “The good news is that from 1975 to 2016, the prevalence of undernutrition in children aged 5 years and older decreased, and obesity in some regions had slowed. The bad news is that the prevalence of overweight and obesity in adults and children and adolescents in other regions of the world was increasing.”

In a statement reacting to The Lancet findings, Nathalie Farpour-Lambert, MD, PhD, president-elect of the European Association for the Study of Obesity, said a “whole-system response” is needed to combat the epidemic of childhood obesity.

“As childhood obesity has a strong tendency to track into adulthood, most children and adolescents who have obesity will have obesity in adulthood and will have a significant lifelong exposure,” Farpour-Lambert said in a press release. “Childhood is a unique window of opportunity to have a lifetime impact on health, quality of life and prevention of disabilities. Therefore, urgent action is needed.” – by Regina Schaffer

Disclosures: The Wellcome Trust and AstraZeneca Young Health Program funded this study. One of the study authors reports he received a charitable grant from the AstraZeneca Young Health Program, and personal fees from Prudential, Scor and Third Bridge. Dietz reports he received consulting fees as a member of the scientific advisory committee for Weight Watchers, as a member and chair of the JPB Foundation’s poverty advisory board and as a consultant for the Research Triangle Institute: Feeding Infants and Toddlers Study, as well as a grant from Bridgespan.