Around this time every year, the height and weight of over 95% of children in the first and final years of primary school in England are measured as part of the National Child Measurement Programme (NCMP). With childhood obesity levels rising, this data set is put to use to identify and support parents whose children are at risk.
In most local authorities, carefully worded letters are sent home to parents whose children are overweight, making them aware of this and offering support to bring about change. But only a handful of parents take up offers of support, and many have publicly expressed the anger and distress they feel on receiving feedback that their child is overweight. Indeed, some health experts have called for an overhaul of the so-called "fat letters".
As a researcher who has been working with public health teams and Public Health England to try and improve the feedback process and impact on parents, I know it can be tempting to dismiss some parents' negative reactions as rare exceptions, or perceive them as a temporary distress that parents need to go through before accepting the truth about their child.
But after 12 years, one thing has become clear: the way we are using the NCMP data is alienating, rather than engaging, the families we really want to reach – so perhaps it's public health professionals, and not parents, who need to change.
Why doesn't it work?
Parents raise many very reasonable objections to feedback that their child is overweight. For example, some argue that their child looks normal (which may be true, now that one in three ten- to 11-year-olds are overweight).
Others say that their child has started puberty, so should be judged by different criteria. Again, this may be true; recent analysis suggests that up to 32% of early-maturing ten- to 11-year-old girls considered overweight according to their chronological age would not be considered overweight if their level of maturity were taken into account.
Parents also report real fears that talking to children about being overweight could harm their self-esteem and well-being, and ultimately lead to eating disorders. While there's no evidence that one leads to the other, discussions with children about losing weight are associated with poorer well-being.
Parents also lack confidence that they are capable of making a difference, especially if they have struggled with their own weight in the past. Where this is the case, parents don't consider taking action to be worth the potential risks to their child's well-being.
These objections raise some genuine challenges, but don't fully explain why some parents might consider these arguments more compelling than factual information about their child's health. At the root of this problem is the stigma attached to obesity and overweight people.
Decades of research shows that the public and health professionals alike have an unconscious bias against overweight people, who are attributed with bad qualities such as gluttony and laziness. And it's normal for humans to respond emotionally to judgements that may be stigmatising, and to try and distance ourselves from stigmatised groups by looking for reasons not to trust such judgements.
So however sensitively worded the letter is, when it communicates that a child is overweight, this news will always trigger an impassioned and defensive reaction to the stigma implied.
From all the research I've read and conducted on this topic, it's apparent that parents feel the health messages around childhood obesity speak to someone else's priorities, rather than their own. Parents are not disinterested in their child's long-term physical health – far from it – but they do feel a more pressing responsibility for their child's well-being here and now.
The more we focus on the physical health risks of childhood obesity, while failing to acknowledge where this may conflict with parents' own decisions, the more parents may feel we are challenging their right to decide what is best for their child's health.
So what next?
Parents have rightly challenged some of the assumptions that weight feedback letters are based on. They have argued that providing feedback can actually risk harm to children, for example by triggering parent-child conversations about weight that wouldn't otherwise happen. While researchers in other fields have pointed out that having an awareness of a child's weight may not be a requirement for changes in diet or activity levels to take place.
Given that NCMP feedback letters show no objective effect on the uptake of child weight management services or reduction in obesity levels, perhaps public health professionals owe it to parents to consider alternatives, rather than press ahead with more of the same.
NCMP data tells us where childhood obesity is more prevalent at the community level – not just for individuals. So the data could also be used to target environmental or community-based responses, such as supporting after school physical activities in schools where obesity is most prevalent. It could also be used to invest in community development initiatives in areas of high obesity, for example by offering grants to community groups, setting up family healthy cooking and activity events and coordinating local media campaigns.
If public health professionals stop triggering parents' defensive reactions by informing them that their child is overweight, they could be more receptive to initiatives which foster healthier behaviours. And surely that's better for everyone.
Explore further: Most parents don't believe their child's BMI report card