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BMI data for children measured as part of the NCMP

BMI data for children measured as part of the National Child Measurement Programme (NCMP) by collection year, school year and sex.
Date published:
20 June 2025

Request received

The full distribution of BMIs for children measured as part of the National Child Measurement Programme for each year going back to 2006, for reception and year 6 pupils, for both boys and girls.

The proportion of children that would meet the clinical definitions of overweight and obese because their BMIs place them at or above the 91st or the 98th centile of the reference population.

Our response

The attached Excel workbook contains two tables that supply the data requested for all NCMP collection years (2006/07 to 2023/24 inclusive).

Table 1

Number and percentage of children meeting the clinical definitions of overweight and obesity, by NCMP collection year, school year and sex.

Note: Clinical definitions of overweight and obesity are based on BMI z-scores (measures of standard deviation). Overweight BMI z-score is >=4/3 and <2. Obesity BMI z-score is >=2. The equivalent BMI centiles (to 4 decimal places) are: overweight BMI centile is >=90.8789 and <97.7250 (often referred to as greater than or equal to 91st centile). Obesity BMI centile is >=97.7250 (often referred to as greater than or equal to 98th centile). See notes 3 and 4 below for more information.

Table 2

Number of children within each BMI centile by NCMP collection year, school year and sex.

Notes
  1. NCMP uses the British 1990 child growth reference (WHO-UK90) to assign each child a Body Mass Index (BMI) centile. Children are growing so BMI is adjusted for sex and age. This approach takes into account each child’s height, weight, sex and age.
  2. UK90 growth reference is recommended by NICE1 and the RCPCH2 for assessing the weight status of children in England.
  3. Surveillance: For population-monitoring purposes, a child’s body mass index (BMI) is classed as overweight or at risk of obesity where it is on or above the 85th centile or 95th centile, respectively, based on the British 1990 (UK90) growth reference data. The population monitoring cut-offs for overweight and obesity are lower than the clinical cut-offs (91st and 98th centiles for overweight and obesity) used to assess individual children - this is to capture children in the population in the clinical overweight or obesity BMI categories and those who are at high risk of moving into the clinical overweight or clinical obesity categories. This helps ensure that adequate services are planned and delivered for the whole population to treat and prevent obesity and promote healthy growth for all children. The UK90 population thresholds were adopted by Health Survey for England in 20023, the NCMP followed in 2006 and uses the same thresholds)4.
  4. Clinical: For clinical purposes and providing feedback to parents the clinical thresholds of UK90 growth reference are used to categorise a child’s BMI using the following categories6:
    • underweight: less than the 2nd centile
    • healthy weight: greater than or equal to the 2nd centile and less than the 91st centile
    • overweight: greater than or equal to 91st centile
    • obesity: greater than or equal to 98th centile
    • severe obesity: greater than or equal to 99.6th centile

References

  1. National Institute for Health and Care Excellence. Overweight and obesity management. NG246. January 2025
  2. Royal College of Paediatrics and Child Health. Child Growth Charts.
  3. [ARCHIVED CONTENT] The Health of Children and Young People. Chpt. 9 Anthropometric measurements, overweight, and obesity
  4. Changes in BMI category of children between the first and final years of primary school, 2023 to 2024_7.5_Body mass index clinical classification and definitions 
  5. Cole TJ, Freeman JV and Preece MA. Body mass index reference curves for the UK, 1990. Archives of Disease in Childhood 1995: volume 73, pages 25 to 29
  6. National Child Measurement Programme: operational guidance 2024 - GOV.UK

Download the data

Last edited: 20 June 2025 1:22 pm