It doesn’t measure up: tracking kids’ BMIs needs to end

  • Election 24

Sarah Gillborn, University of Birmingham 

In this piece, Sarah Gillborn, University of Birmingham, draws on social science evidence to argue that BMI (Body Mass Index) measurements as part of the National Child Measurement Programme (NCMP) do more harm than good, providing recommendations for what the next UK Government should do to address this challenge.

In England, the National Child Measurement Programme (NCMP) is a key part of the government’s response to childhood obesity. Introduced in 2006, this programme aims to analyse childhood obesity trends at population level and “provide a mechanism for direct engagement with families” by mandating state-maintained schools to measure the BMI (Body Mass Index) of all pupils in Reception (aged 4–5) and Year 6 (aged 10–11). A ‘results letter’ is then sent home to each child’s parents/guardians. Children are assigned to one of four categories – ‘underweight’, ‘healthy weight’, ‘overweight’ or ‘very overweight’ – and a ‘hints and tips’ leaflet about healthy lifestyles is sent to the parents of children outside of the ‘healthy weight’ category.

Evans and Colls have highlighted that when the NCMP was first proposed, the National Screening Committee deemed a BMI screening programme inappropriate on the grounds that it did not have the potential to ‘do more good than harm’. Thus, it was implemented as a monitoring programme instead, the key difference here being that monitoring programmes must not take action at an individual level. In the context of this programme, this would mean that children and parents should not be made aware of the child’s BMI and no advice or guidance must be given to individuals; this, the National Screening Committee argued, could do more harm than good. Despite these warnings, in the 2008/9 academic year, the NCMP was revised to become a screening programme. This change was realised through its inclusion as a ‘small measure’ within the larger Health and Social Care Bill introduced in November 2007. These revisions ignored the earlier problems raised by the National Screening Committee, which included the inability of BMI to measure health and the potential emotional implications of children’s involvement in height and weight measurements.

Although the NCMP is described as “a vehicle for engaging with children and families about healthy lifestyles and weight issues”, the NCMP’s own annual reports reveal that there has been no significant positive change in rates of childhood obesity since the programme’s inception. This is not, however, the most pressing issue with the programme or indeed with children’s health.

First, BMI is criticised by parents and researchers alike as a crude and unreliable measure of health. BMI is a calculation of a person’s weight in kilograms divided by the square of height in meters; it was originally derived from an observed pattern in body size from clinical observations. It was not based on clinical assessments of the relationship between body size and health, and shouldn’t be used to assess health. The measure also fails to differentiate between different types of mass; so, BMI tends to overestimate body fat in those with high muscle mass, and underestimate it in those with a low lean body mass. For example, Dwayne ‘”The Rock” Johnson would be considered ‘obese’, and therefore at risk of poor health, if BMI is to be believed.

Further evidence of this lies in repeated evidence showing that, when BMI is used as an indicator of health, millions of people are misidentified as either healthy or unhealthy. This same evidence demonstrates that people can be both; and, in fact, the weight fluctuation that is common among those who frequently attempt to lose weight appears to contribute to the health issues for which obesity is often blamed. This seems to show that encouraging weight loss may be unnecessary and even physiologically harmful to many.

A second important issue with the NCMP is the striking lack of action around rising childhood poverty in the UK, and perhaps relatedly, evidence suggests that the children marked as ‘underweight’ through the NCMP are not treated with the same urgency as those who are ‘overweight’. This is particularly evidenced by the lack of references to underweight in the NCMP policy documents and, when ‘underweight’ is referenced, it is frequently accompanied by reassurances that are absent from the many mentions of ‘overweight’ and ‘obesity’ (e.g. “most underweight children are perfectly healthy”). In a programme seeking to support families to work towards healthy lifestyles, this absence seems glaring; it is perhaps because, while obesity is often assumed to be the result of individual fault, underweight cannot easily be blamed on parents without considering the impact of wider contextual issues such as poverty. Further, this perhaps indicates that the key goal is not in fact to get all children to a ‘healthy weight’, but to instead tackle levels of ‘obesity’ and ‘overweight’ more specifically. Thus, it appears that health in and of itself is not in fact the priority here so much as the ‘war on obesity’.

As readers may predict, evidence suggests that the screening process does indeed do more harm than good to children and their families. Parents have described their children developing “body complex issues” following measurements. Adults with eating disorders have referred to similar obesity campaigns having directly fed into the development of their eating disorders. And parents – particularly mothers, who are predominantly held responsible for their children’s bodies – are themselves harmed by the programme, battling between acknowledging their child’s ‘weight problem’ while wanting to encourage healthy relationships with their bodies. If the health and wellbeing of children is truly a priority then a BMI screening programme, with its clear implications and the repeated evidence to demonstrate the futility of BMI as a measure of health, is not up to task.

The failure of the NCMP to support children’s health is built into its foundations as a BMI screening programme. The reliance on BMI reproduces harmful and evidently incorrect assumptions of health as directly related to weight, reinforcing harmful notions of the ‘ideal’ body and contributing to eating disorders and mental health difficulties. The NCMP’s focus on engaging with parents to change children’s weight obscures much-needed conversations and interrogations about the impact of government policy on children’s health and wellbeing. While there is no evidence to suggest the NCMP has any positive influence, plenty of evidence shows the harm it may cause.

The next government should scrap the NCMP. The evidence is clear that the programme, as the National Screening Committee warned early on, does more harm than good with regards to children’s health. Looking to the roots of the NCMP and the ideas about health on which the programme is built, the next government should also see childhood (and adult) health as beyond the limited scope of BMI, instead understanding health as encapsulating both physical, psychological, and community wellbeing that cannot be predicted by measuring body size. Ultimately, a relevant policy change here is also the end of austerity, which has decimated services that were vital in supporting parents and families. The next government should not hold parents responsible for children’s health while removing the resources that would support families to lead physically and psychologically healthy lives.

About the author

Sarah Gillborn is a Lecturer in Psychology in Education in the Department of Education and Social Justice. She is a critical psychologist interested in critical feminist and qualitative research. Sarah’s research focuses on analyses of discourse and voice, particularly in relation to public policy, in order to understand how social issues are officially constructed and re/negotiated by those implicated by them. In addition, Sarah’s work takes a critical look at the role of psychology as a discipline in reproducing and challenging oppression.

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