The overlooked factor driving the childhood obesity crisis

Ibbie, 16, always struggled with her weight, but it was during the Covid-19 lockdowns that she started eating even more. She was bullied by classmates over her size, and in her first year of secondary school she stopped attending completely.

Away from the routine of the school day, her weight problems worsened.

"When you are at home 24/7 it is very easy to go into the kitchen to get a snack. It's not the same if you are at school," says Ibbie, from Doncaster.

By the age of 12 she weighed nearly 22 stone (140kg) and was diagnosed with liver damage. "I was told that I might need to have a liver transplant if I didn't lose weight. That was scary to hear."

Ibbie's experience is one of the more extreme examples of children living with obesity in the UK – but her story is not unique. She is one of more than 6,000 children who have been treated at a pioneering weight-loss service for the most obese children in the country. These Complications from Excess Weight (CEW) clinics are a network of 39 specialist NHS hubs across England designed to treat severe obesity in children.

Some of the young people treated at the clinics have mental health problems and learning disabilities; others are neurodiverse or autistic.

But there's one characteristic that unites nearly all the children: they do not attend school.

The scientific picture is still emerging, but senior doctors who have spoken to the BBC say that school attendance is emerging as a key, overlooked factor in the battle against childhood obesity.

In the 2000s, when Jamie Oliver was touring British schools for his influential Channel 4 series, it was argued that children were getting fat from buying too many turkey twizzlers at the school canteen.

Now, it's being away from school that seems to be a problem, scientists say.

Childhood obesity has been rising in the UK for decades, and scientists have generally identified a simple culprit: increased consumption of junk food.

But then, in 2020, it became more complicated. While childhood obesity had been rising steadily long before the pandemic, the rates exploded during the lockdowns. The proportion of overweight and obese 10 and 11-year-olds rose from 35% to 41%, with poorer children disproportionately affected.

Although obesity levels have come down since, they have never returned to pre-pandemic levels. The most recent government data shows that one in 10 children starting school in England is obese, but that figure rises to one in five by the time children leave primary school.

Prof Ken Ong, the lead clinician at Cambridge University Hospital's CEW clinic, believes that the current high level of childhood obesity is rooted in the school time that was missed during the pandemic. "We do know that diets got worse. We do know that children did a lot less physical activity. We know that for many children, they became quite isolated being taken out of schools," he says. "I think these are the same factors that are and have been contributing to overweight and obesity."

It's well-documented that even short periods of time out of school, like the summer holidays, can lead to an increase in children's weight. And since the pandemic, fewer British children are attending school altogether. In 2019, about 10% of pupils at English state schools were classed as "persistently absent", meaning they missed at least 10% of classes. Now, it is 18%.

We don't have official, UK-specific data tracking the connection between obesity and school absence, but international research has historically suggested a connection. A meta-analysis published in 2017, which looked at research across seven countries, suggested that an obese child was 54% more likely to be absent from school compared to a child with a healthy weight.

There has been no extensive research in Britain on why school absence might be causing obesity, but doctors who have spoken to the BBC have their theories.

One factor is diet. Since the 2000s - when all four UK governments passed laws to make school lunches healthier - it's become much harder to find high-sugar or high-fat foods in most canteens. At home, those restrictions don't apply. By 2010, a few years after the new laws were introduced, a study from the University of Leeds found that only 1.1% of home-packed lunches met the nutritional requirements that would apply to a meal bought by a child at school.

And a US study from earlier this year found that child obesity rose in states where a universal free school meal programme was withdrawn in 2022 (presumably because it prompted children to eat unhealthy food at home).

"While school food is not as good as it should be, there are some regulations around it," says Keith Godfrey, an epidemiology professor at the University of Southampton. "Whereas in the home environment, it's much more variable in terms of what children receive."

Exercise also matters. A British study from 2014 looked at step counts measured with electronic sensors, and found that most children are more active on school days than weekends.

Dr Catherine Falconer, a leading researcher who has looked at the link between child health and school absence (and who also works for the UK Health Security Agency), says there's "quite strong evidence that going to school has a big impact on health". She adds: "The very act of leaving the house and walking to school is beneficial."

The science is not yet settled, of course, and it can be difficult to disentangle cause from effect. School absence might be driving obesity - but it's also possible that obesity is making children miss school.

And everyone agrees that if school absence is causing obesity, it's just one of many causes. Other factors - like the proliferation of ultra-processed foods - also matter. And there are thousands of home-schooled children in Britain who maintain a perfectly healthy weight.

But scientists who have spoken to the BBC say they are confident that, at least in some cases, school absence is playing a key causal role.

"School attendance is key," says Prof Simon Kenny, NHS England's national clinical director for children and young people, and the man who launched the first CEW clinics in 2021. "I hadn't quite clocked how absent these children are not just from school but from life. You don't see them in the street or youth clubs or sports centres. They are outside of society."

And it can lead to unhappiness. Prof Julian Hamilton-Shield, a consultant paediatrician at the Bristol Royal Hospital for Children, says that the severely obese children he treats are "the most unhappy children I have come across".

Ibbie, the 16-year-old treated at Sheffield's CEW clinic, remembers some dark days. "The bullying got so bad… there was physical bullying as well as verbal," she remembers. "I had suicidal thoughts. It got to the stage where I actually tried to take my own life."

One approach is to send health workers directly into schools to deliver personalised health plans. The CEW clinics have tried just this approach.

Tessa Saunders, a family therapist at Cambridge's CEW clinic, says that schools should in some cases allow children to follow their own diet plans - even if it means breaking school rules. Obese children could be given extra time in the canteen, she says, to help them slow down their eating so their bodies have more time to feel full. And they could be offered an extra snack in the afternoon so they're not tempted to overeat when they get home.

She admits it might "seem weird" if obese children are given more food than other children. But, she says, "there's a reason behind it. It's not the mum trying to make her kid the special one."

She says teachers could also closely monitor the water intake of obese children (sometimes when children think they feel hungry, they are actually thirsty).

"I think in this country we have been focused on school attendance being a school problem," Dr Falconer says. "School absence should be treated as a public health issue."

She also thinks that reversing the decline in school nurses could help spot vulnerable children sooner. "I think there is a real potential around schools being a place you can receive some level of healthcare, whether it's around healthy eating, vaccinations or dental care."

Of course, it takes work to get a child back into school after a long period of absence. Some parents who attend the clinic hope there might be an easier solution to their child's obesity: weight-loss drugs like Mounjaro and Ozempic, known as GLP-1s.

The drugs are only licensed for children aged 12 and over, and they aren't routinely recommended for anyone under 18, under guidelines from the UK's National Institute for Health and Care Excellence.

Prof Ong says he has encountered parents at his clinic who want access to weight-loss jabs - an easier option, perhaps, than getting a child back into school.

And many doctors see their promise. They point out that obesity in children is a potentially life-threatening condition if left untreated for decades. Prof Julian Hamilton-Shield says he's seen weight-loss drugs have a transformative effect on the self-esteem of severely obese teenagers.

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Around the same time as she dropped out of school, Ibbie was given GLP-1 injections as part of her treatment at the Sheffield CEW clinic. She was just 12 years old. She lost 10 stone (64kg) and is now much healthier. "It has completely changed my life," she says. "I actually started losing weight before taking the drugs just to prove to myself I could do it. After losing the extra weight I no longer have liver failure, I am no longer prediabetic. I am a lot happier and more confident in myself."

Some parents who are desperate to find a solution to their child's obesity have resorted to buying the drugs privately online. "These parents have the best possible intentions," Prof Hamilton-Shield says, "but I can't advocate for that."

But Prof Ong cautions that weight-loss drugs alone aren't going to offer severely obese children the life-changing health benefits they need.

"Some families see weight-loss medication as a quick fix," he says. "Families who come here have very complex needs and if those aren't addressed then either the weight will come back very quickly, or the medication is papering over the many other needs of these children."

Ultimately, he thinks, it's more important for a child to build a healthy routine - and that means regular attendance at school.

Doctors say that getting obese children back into school could be a key tool to address the childhood obesity crisis. But obstacles remain. The current network of 39 CEW clinics in England reaches just 5% of the obese children that are eligible. The annual cost of treating obesity-related ill health (for all ages) in the NHS is now estimated at £12bn.

Although Ibbie became fitter and healthier, she never did return to school. She says the bullying she received from classmates was so bad she developed symptoms of PTSD. Instead she was home-schooled by her mother, Andrea, with a schedule that included plenty of history field trips. Ibbie's year group took their GCSEs this summer; Ibbie is yet to take them.

But she hasn't given up on education. Inspired by her time at the clinic, she now hopes one day to study healthcare at college. "I just know how life-changing the support in the clinic was for me," she says. "I want to help other people too."

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