- BMI (body mass index)
- Weight in kilograms divided by height in metres squared. A quick way to compare weight across people of different heights.
- Obesity (adults)
- A BMI of 30 or more.
- Overweight (adults)
- A BMI of 25 or more. In WHO figures this group includes people with obesity.
- Severe obesity
- A BMI of 40 or more, also called class 3 obesity.
- BMI-for-age
- For children and teens, BMI compared with other young people of the same age and sex, using a growth reference.
- Prevalence
- The share of a group that has a condition at a given time — for example “16.4% of the world’s adults live with obesity” (WHO, 2024).
- Age-standardized
- Adjusted so that countries with older or younger populations can be compared fairly, as if they all had the same age mix.
- Crude rate
- The actual share in the real population, without age adjustment. Used when counting people.
- Uncertainty interval / confidence interval
- The range the true value is likely to fall in. Shown as shaded bands on our charts.
- Measured vs self-reported
- Measured = someone weighed and measured you. Self-reported = you told a survey your height and weight.
- Percentage points
- The difference between two percentages. Going from 10% to 15% is a rise of 5 percentage points (which is a 50% increase).
- WHO region
- One of six groups of countries used by the World Health Organization: Africa, Americas, Eastern Mediterranean, Europe, South-East Asia, Western Pacific.
- Double burden of malnutrition
- Undernutrition and overweight or obesity found side by side in the same country, community or even household.
Last updated
Written by the ObesitySurvey team. Not medical advice.