Childhood overweight and obesity

WHO defines overweight and obesity as abnormal or excessive fat accumulation that presents a risk to health.

Childhood obesity is a chronic disease driven by complex interactions between environmental, social, biological and behavioural determinants. It is a major global public health challenge affecting people in all regions of the world.

The prevalence of overweight among children and adolescents aged 5–19 years increased from 8% in 1990 to 20% in 2024.

Overweight and obesity in childhood and adolescence can adversely affect physical, mental and social well-being. Without timely intervention, obesity often persists into adulthood, increasing the risk and accelerating the onset of noncommunicable diseases, including type 2 diabetes and cardiovascular disease. Overweight and obesity, as well as their related noncommunicable diseases, are largely preventable and manageable.

WHO defines overweight and obesity as outlined below.  

Children under 5 years of age

• overweight is weight-for-height greater than 2 standard deviations above WHO Child Growth Standards median; and
• obesity is weight-for-height greater than 3 standard deviations above the WHO Child Growth Standards median.

Charts and tables: WHO child growth standards for children aged under 5 years

Children and adolescents aged 5–19 years

• overweight is BMI-for-age greater than 1 standard deviation above the WHO Growth Reference median; and
• obesity is greater than 2 standard deviations above the WHO Growth Reference median.

Charts and tables: WHO growth reference for children aged between 5–19 years

Childhood obesity is associated with a higher chance of premature death and disability in adulthood. Overweight and obese children are more likely to stay obese into adulthood and to develop noncommunicable diseases (NCDs) like diabetes and cardiovascular diseases at a younger age. For most NCDs resulting from obesity, the risks depend partly on the age of onset and on the duration of obesity. Obese children and adolescents suffer from both short-term and long-term health consequences.

The most significant health consequences of childhood overweight and obesity, which often do not become apparent until adulthood, include:

• cardiovascular diseases (mainly heart disease and stroke)
• diabetes
• musculoskeletal disorders, especially osteoarthritis
• certain types of cancer (endometrial, breast and colon).
  

In 2021, higher-than-optimal BMI caused an estimated 3.7 million deaths from noncommunicable diseases (NCDs) such as cardiovascular diseases, diabetes, cancers, neurological disorders, chronic respiratory diseases, and digestive disorders (1).

Many low- and middle-income countries are now facing the so-called double burden of disease. As they continue to struggle with the problems of infectious diseases and under-nutrition, at the same time they are experiencing a rapid increase in risk factors of NCDs such as obesity and overweight, particularly in urban settings.

It is not uncommon to find under-nutrition and obesity existing side by side within the same country, the same community or even within the same household in these settings.

This double burden is caused by inadequate prenatal, infant and child nutrition, which is then followed by exposure to high fat, energy dense, micronutrient poor foods and a lack of physical activity as the child grows older.

The causes of childhood overweight and obesity are complex and influenced by multiple factors, including biological, behavioural, social and environmental factors.

Global increases in childhood overweight and obesity are attributable to several factors. There has been a global shift in diet towards increased intake of energy-dense foods that are high in fat and sugars but low in vitamins, minerals and other healthy micronutrients. There is also a trend towards decreased physical activity levels due to the increasingly sedentary nature of many forms of recreation time, changing modes of transportation and increasing urbanization.

WHO recognizes that the increasing prevalence of childhood obesity results from changes in society. Childhood obesity is influenced by the environments in which children live, as well as social and economic development and policies in the areas of agriculture, transport, urban planning, the environment, food processing, distribution and marketing, as well as education.

The problem is societal and therefore it demands a population-based multisectoral, multidisciplinary and culturally relevant approach.

Children and adolescents cannot choose the environment in which they live or the food they eat.

Overweight and obesity, as well as related noncommunicable diseases, are largely preventable.

Prevention and treatment of childhood and adolescent obesity need to go together. Countries need to create environments that make healthy diets and physical activity accessible and affordable, while ensuring that children and adolescents already living with obesity have access to appropriate care and support.

For children and adolescents living with obesity, WHO recommends structured support for healthy eating, physical activity and behaviour change. This includes:

• structured dietary interventions;
• structured physical activity interventions;
• behaviour-change interventions; and
• multimodal interventions that combine diet, physical activity and behavioural components (1, 2).

These interventions should be tailored to the individual needs and circumstances of children and adolescents and involve parents and/or caregivers. Digital health interventions may also be considered as part of an integrated approach to obesity management.

For adolescents aged 10–19 years, additional treatment options may be considered under specific conditions. Pharmacological treatment may be considered for adolescents living with obesity and obesity-related complications after a structured and supervised programme of multimodal lifestyle modification has failed to achieve results. For adolescents with severe obesity, bariatric surgery may also be considered under strict conditions and with appropriate support.

Bending the curve on childhood obesity requires sustained political commitment, with prevention and treatment going together.

Governments, international partners, civil society, NGOs and the private sector have vital roles to play in shaping healthy environments and making healthy diets and physical activity affordable and easily accessible for children and adolescents. This includes regulatory and fiscal measures to improve food environments, as well as action across education, urban planning, transport and social protection.

At the same time, health systems need to ensure that children and adolescents living with obesity have access to high-quality care, free from stigma and discrimination.

WHO supports countries in advancing population-level prevention, targeted interventions for people at increased risk, and comprehensive clinical care for people living with obesity. A multisectoral approach is essential for sustained progress.