Trends in prevalence of overweight and obesity among South African and European adolescents: a comparative outlook

BACKGROUND: South Africa has several national surveys with body weight-related data, but they are not conducted regularly. Hence, data on longitudinal trends and the recent prevalence of adolescent obesity are not readily available for both national and international reporting and use. This study collectively analysed nationally representative surveys over nearly 2 decades to investigate trends in prevalence of adolescent obesity in South Africa. Furthermore, it compared these data with similar continental report for 45 countries across Europe and North America including United Kingdom, Norway, Netherland, Sweden, Azerbaijan, etc. to identify at-risk sub-population for overweight and obesity among adolescents. METHODS: The study included primary data of adolescents (15 – 19 years) from South African national surveys (N = 27, 884; girls = 51.42%) conducted between 1998 and 2016. Adolescents’ data extracted include measured weight, height, sex, parent employment status, monthly allowance received, and family socioeconomic-related variables. Data were statistically analysed and visualized using chi-square of trends, Wald statistics, odds ratio and trend plots, and compared to findings from European survey report (N = 71, 942; girls = 51.23%). South African adolescents’ obesity and overweight data were categorized based on World Health Organization (WHO)’s growth chart and compared by sex to European cohort and by family socioeconomic status. RESULTS: By 2016, 21.56% of South African adolescents were either obese or overweight, similar to the 21% prevalence reported in 2018 among European adolescents. Girls in South Africa showed higher trends for obesity and overweight compared to boys, different from Europe where, higher trends were reported among boys. South African Adolescents from upper socioeconomic families showed greater trends in prevalence of overweight and obesity than adolescents from medium and lower socioeconomic families. Mothers’ employment status was significantly associated with adolescents' overweight and obesity. CONCLUSIONS: Our study shows that by 2016, the prevalence of adolescent obesity was high in South Africa – more than 1 in 5 adolescents – which is nearly similar to that in Europe, yet South African girls may be at a greater odd for overweight and obesity in contrast to Europe, as well as adolescents from high earning families. South African local and contextual factors may be driving higher prevalence in specific sub-population. Our study also shows the need for frequent health-related data collection and tracking of adolescents’ health in South Africa.