Every year, the government weighs and measures children in Reception (ages 4-5) and Year 6 (ages 10-11). The National Child Measurement Programme isn’t always popular with parents but it gives us priceless public health information on hundreds of thousands of children. With such a robust data set, it gives us the ability to look at how children change over time and test some of the theories that get thrown around about childhood growth and obesity.
During the summer, a report from the Food Foundation claimed that the average height of five year olds was falling and had been since 2013. Gordon Brown thundered that this was down to ‘food bank Britain’ and experts previously ascribed this to government austerity in the 2010s.
But is this actually true? This is what the government data shows:
Except for the blip during the pandemic, when data collection was obviously difficult, there’s very little change in the average height, and perhaps even a small increase for boys. If the issue was poverty and malnutrition, it might be masked by the average – so let’s take a look at the most deprived 10 per cent:
If anything, the upwards trend is more marked, suggesting that the poorest five year olds have got slightly taller in the last 15 years. The effect is even stronger when we look at older children:
Although poorer boys are still typically shorter than their wealthier counterparts, in 2023-24 the average 11 year old boys in the most deprived cohort were taller than the least deprived boys five years earlier.
Turning to obesity though, the data does support the commentary from experts, or at least in part. Something really is going badly wrong with the health of our children:
This isn't just a story of children with a bit of extra weight. Obesity, defined by a body mass index over 30, is not a bit of puppy fat – it’s a severe health risk. And while the levels of obesity in younger children have remained relatively stable, there’s a striking increase by the time children reach Year 6. The pandemic – and reduced exercise from lockdown – had a marked effect, but if we ignore that, there’s a clear upward trend in year 6 obesity – which started long before Covid.
For all the government grandstanding on public health in the last few years, the efforts to curb childhood obesity appear to be failing. Experts hailed the sugar tax as a key weapon in the battle of the bulge – but since it was introduced in 2018, Year 6 obesity has, if anything, accelerated. Its main effect seems to be boosting tax revenue.
One thing to keep an eye on for future years is the Reception cohort. There's been a tick up in obesity in the last year. This may just be statistical noise, but it’s worth noting that these children are among the first born during the pandemic. This upheaval in their first few months of life may have affected them but we’ll need more data to see if this is a trend with lasting effects.
Drilling further into the data gives us more cause for concern. In Dickens’s day, the poor were malnourished but now obesity is a disease of deprivation. The most deprived children in society – those who need help the most – are the ones most likely to suffer from obesity. These graphs show stark disparities: children from the poorest backgrounds are more than twice as likely to be obese as their wealthier peers. This isn’t a small gap – it’s a chasm, and it’s widening.
The stakes here are high – not just for these children now, but for their future health. Childhood obesity may do more than simply establish unhealthy habits, it can lead to changes at a cellular level. Recent epigenetic research – examining how external factors influence gene expression – suggests that childhood obesity can accelerate biological ageing and increase the risk of conditions like diabetes later in life. These may be locked in even if weight is later lost.
If the government is serious about tackling childhood health issues, it must base its policies on the evidence in front of it, not on assumptions or vibes. The data from the National Child Measurement Programme reveals clear trends: childhood obesity is rising, particularly among the most deprived, while average height is steady or increasing among the poorest children. These insights challenge some lazy narratives and point to complex underlying causes that won’t be solved by quick fixes like the sugar tax or calls for more PE lessons.
If policy-makers want to make real progress, they need to focus on the factors that the data identifies as most urgent – and commit to solutions grounded in research and rigorous evaluation, not just well-meaning intentions.
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