Primary 1 Body Mass Index (BMI) statistics Scotland
School year 2023 to 2024

About this release

This annual release from Public Health Scotland (PHS) provides statistics on high, low and healthy body mass index (BMI) for Primary 1 school children (those aged around 5 years old), and includes data for school years 2001/02 to 2023/24. Statistics in this release are derived from height and weight measurements collected at health reviews in Primary 1.

Main points

• In school year 2023/24, 76.5% of Primary 1 children measured had a healthy weight, 22.3% were at risk of overweight or obesity and 1.2% were at risk of underweight.

Figure 1 is an area chart showing that there was little change in the percentage of children in each of the weight categories since 2001/02, until the drop in healthy weight in 2020/21, and then it increased again after that.

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Figure 1: BMI distribution of Primary 1 Children, school years 2001/02 to 2023/24, Scotland

Note: Individual NHS Boards implemented data collection at different times, with all areas providing data from 2011/12 onwards, but coverage was much lower in 2019/20 and 2020/21 due to COVID-19.

•  Marked socioeconomic inequalities in child healthy weight persist, particularly in the percentage of children at risk of obesity. In 2023/24 14.0% of children living in the most deprived areas were in this category, compared with 6.4% of those living in the least deprived areas.
• In 2023/24 children of Black, Caribbean or African ethnicity were most likely to be at risk of obesity (13.6%) and children of White Other British ethnicity were least likely (8.0%), with 10.9% of White Scottish children at risk of obesity.
• Boys in Primary 1 remain slightly less likely than girls to have a healthy weight, but a similar proportion of boys (22.3%) and girls (22.2%) were at risk of overweight and obesity.
• In school year 2023/24 a total of 46,889 children had valid height and weight measurements recorded in Primary 1. This is approximately 89% of children aged 5 in Scotland.

Background

A child’s BMI is calculated by dividing their weight (in kilograms) by their height (in metres) squared. Children are then allocated to a healthy or unhealthy weight category by comparing their BMI to the range of BMIs seen among a reference group of children of the same age and sex.

This summary provides information on the proportion of children found to be at risk of having an unhealthy weight based on the thresholds used for monitoring the health of the child population (‘epidemiological thresholds’).

The full report also provides information on the proportion of children found to have an unhealthy weight based on the narrower clinical thresholds used by health professionals caring for individual children. Monitoring healthy weight across the child population is a way of seeing how well the needs of children are being met. Maintaining a healthy weight through childhood is associated with many health benefits.

Further information

The next release of this publication will be December 2025.