Description:
This indicator measures the proportion of adults (aged 16+) and children (aged 2-15 years old) who are a healthy weight.
Source of Data:
The data for this indicator comes from the Scottish Health Survey (SHeS).
SHeS provides a detailed picture of the health of the Scottish population in private households and SHeS data is published on the Scottish Government website, here Scottish Health Survey - gov.scot (www.gov.scot)
Definitions:
Body Mass Index (BMI) is a widely accepted measure that allows for differences in weight due to height. It is defined as weight (kg)/square of height (m2).
Height and weight measurements have been collected during the survey interview every year since its inception in 1995. SHeS is one of a small number of surveys that collects height, weight and waist measures rather than using self-reported measures, which are known to be less accurate. Height and weight are used to calculate Body Mass Index (BMI),
In 2021, due to the impact of the pandemic, it was not possible to interview SHeS participants in their homes and interviews were conducted via telephone instead. It was therefore not possible to obtain the standardised height and weight measurements. Where they were happy to do so, participants were asked to estimate their height and weight, with these self-reported measures used to calculate estimated BMI.
Work undertaken to analyse data from the Health Survey for England (HSE) and Active Lives Surveys found that, on average, participants overestimated their height and underestimated their weight. Adjustments for adults have been made to account for this and while these corrections appear to remove some bias from the estimates, caution is advised in interpreting this data.
Based on their BMI adult participants were classified into the following groups based on the World Health Organisation (WHO) classification:
BMI (kg/m2)
- Less than 18.5 Underweight
- 18.5 to less than 25 Normal
- 25 to less than 30 Overweight, excluding obesity
- 30 to less than 40 Obesity, excluding morbid obesity
- 40+ Morbid obesity
The BMI data presented for this indicator in 2021 is based on data that has been adjusted according to the formula from this HSE and Active Lives work referenced previously.
Based on their BMI (calculated from self-reported height and weight), child participants were classified into the following groups based on the World Health Organisation (WHO) classification.
Although the BMI calculation method is the same, there are no fixed BMI cut-off points defining overweight and obesity in children. Instead, overweight and obesity are defined using several other methods including age and sex specific BMI cut-off points or BMI percentile cut-offs based on reference populations. While the data for adults has been adjusted based on previous comparator analysis, no equivalent analysis was available for children, therefore, these self-report figures have not been adjusted.
Children can be classified into the following groups:
BMI (percentile)
- Above 2nd and below 85th Within healthy range
- At or above 2nd, at or above 85th Outwith healthy range
- At or above 85th, below 95th At risk of overweight
- At or above 95th At risk of obesity
Criteria for Change
This evaluation is based on: An annual change in the percentage of children who are a healthy weight that is significant at the 95% confidence limits or an annual change in the percentage of adults who are a healthy weight that is significant at the 95% confidence limits.
A significant increase either in adult or children’s’ weight will result in the arrow showing performance improving.
A significant decrease either in adult or children’s weight will result in the arrow showing performance worsening.
If there is no significant change for adult or children’s weight or if there is a significant change for both but in opposite directions then the arrow will show performance maintaining.
We will review the situation with the Scottish Health Survey data once the next available data is published for 2022 and amend any indicator change criteria as necessary.