WIREDGOV

Obesity rates in primary school children dropped in 2021/22 after reaching highest recorded levels the previous academic year, new provisional figures from NHS Digital show.

Notes for editors

1. The obesity prevalence includes severely obese children.

2. In the statistical publication text and excel tables, percentages are usually shown to one decimal place. The excel tables contain more decimal places.

3. Each year, children in reception and year six are measured. This means that a separate set of children are measured each year and there is no follow up of specific cohorts (other than the six years of elapsed time when reception children become year six children). For example, the children measured in 2021/22 were different children from those measured in 2020/21.  

4. The National Child Measurement Programme (NCMP) – overseen by the Office for Health Improvement and Disparities (formerly Public Health England) and analysed and reported by NHS Digital – was launched in the 2005-06 academic year and now holds 16 years of reliable data. 2006-07 is the first year that the data are considered to be robust due to the low participation in 2005-06, so this is the earliest year that comparable data for obesity prevalence among reception-aged children is available. 2009-10 is the first year that the obesity prevalence figures are robust for year 6 schoolchildren.

5. The BMI classification of each child is derived by calculating the child’s BMI centile and classifying as follows:

   • BMI centile <=2: Underweight
   • BMI centile >2 and <85: Healthy weight
   • BMI centile >=85 and <95: Overweight
   • BMI centile >=95: Obese
   • BMI centile >=99.6 Severely obese.
     Note: “Severely obese” is a subset of “Obese”. Children with a BMI centile of between 95 and 100 are classified as “Obese” and those with a BMI centile of between 99.6 and 100 are classified as “Severely obese”

   This calculation uses age and sex as well as height and weight to take into account different growth patterns in boys and girls at different ages. A child’s BMI centile is a measure of how far a child’s BMI is above or below the average BMI value for their age and sex in a reference population. The NCMP uses the British 1990 growth reference (UK90) to define the BMI classifications.  This approach was recommended by The National Institute for Health and Care Excellence (NICE). See “Calculation of prevalence” in Appendix A of the report for more details.

6. Data is collected primarily in mainstream state-maintained schools in England. Any data collected from independent or special schools is excluded from this analysis.

7. The National Child Measurement Programme usually measures the height and weight of over one million children in England annually and provides robust data on the number of children in reception and year 6 who are underweight, healthy weight, overweight, obese or severely obese. In 2020-21, due to the coronavirus (COVID-19) pandemic disrupting the collection, 300,000 children were measured. This new publication includes data on 808,809 children who were measured between Sept 2021 and May 2022 and whose measurements had been submitted to NHS Digital by the time the data was extracted on 23 May 2022. Details of the data quality work that was undertaken to assure the underlying data used to produce these provisional results are available in the Methodology and Data Quality section of the publication.

8. The annual NCMP data is expected to be published in November 2022 and will include figures based on the full school year.

9. Comparisons between groups and over time have been statistically tested to determine whether differences are likely to be genuine (i.e. statistically significant) or the result of random natural variation. Only statistically significant differences have been described with terms such as ’higher’, ’lower’, ’increase’ or ’decrease’. When a comparison does not show a statistically significant difference, this is described using terms such as ‘similar to’ or ’the same as’.