Obesity

In plain words

Obesity is a chronic disease driven by complex interactions of environmental, social, biological and behavioural factors. It is linked to rising burdens of type 2 diabetes, cardiovascular disease, liver and kidney disease and several cancers.

Key facts

• In 2024, 1 in 7 people (1.1 billion) lived with obesity.
• Adult obesity has more than doubled since 1990 and adolescent obesity has quadrupled.
• In 2024, 45% of adults (2.6 billion) were overweight, of whom 940 million (16% of all adults) had obesity.
• 35 million children under 5 were overweight, and 400 million children and adolescents aged 5 to 19 were overweight, including 170 million with obesity.

How it is defined

By body mass index (BMI): weight in kilograms divided by height in metres squared. For adults WHO defines overweight as BMI 25 or more and obesity as 30 or more. Categories differ by age and sex for children and adolescents. Waist circumference can also be used.

Context

WHO notes obesity has risen worldwide alongside improved food security and development and major changes in diets, activity patterns and social norms, creating environments that promote unhealthy weight gain.

Sources

• WHO fact sheet, Obesity, published 7 October 2026, read 9 October 2026.

Last reviewed: 9 October 2026. Reviewer: none yet. This page is general education and is not medical advice. Figures are WHO's and may have been updated since.