The epidemiological burden of obesity in childhood: a worldwide epidemic requiring urgent action

Background: In recent decades, the prevalence of obesity in children has increased dramatically. This worldwide epidemic has important consequences, including psychiatric, psychological and psychosocial disorders in childhood, and increased risk of developing noncommunicable diseases later in life. Treatment of obesity is difficult, and children with excess weight are likely to become adults with obesity. These trends have led World Health Organization (WHO) member states to endorse a target of no increase in obesity in childhood by 2025. Main body: Estimates of overweight in children aged under 5 years are available jointly from UNICEF, WHO and the World Bank. Country-level estimates of obesity in children aged from 2 to 4 years have been published by the Institute for Health Metrics and Evaluation (IHME). For children aged from 5 to 19, obesity estimates are available from the NCD Risk Factor Collaboration. The global prevalence of overweight in children aged under 5 years has increased modestly, but with heterogeneous trends in low- and middle-income regions, while the prevalence of obesity in children aged from 2 to 4 has increased moderately. For children aged 5 to 19, obesity was relatively rare in 1975, but was much more common in 2016. Conclusions: It is recognised that the key drivers of this epidemic form an obesogenic environment, which includes changing food systems and reduced physical activity. Although cost-effective interventions such as WHO “best buys” have been identified, political will and implementation have so far been limited. There is therefore a need to implement effective programmes and policies in multiple sectors to address overnutrition, undernutrition, mobility and physical activity. To be successful, the obesity epidemic must be a political priority, with these issues addressed both locally and globally. This must involve coordinated work by governments, civil society, private corporations and other key stakeholders.