Childhood obesity: Why the UK's poorest kids weigh more than the wealthy

The UK has seen a dramatic reversal in the weight of its children over the past 70 years, with a new study exposing how the poorest kids have become [more likely to be obese](http://www.thelancet.com/pdfs/journals/lanpub/PIIS2468-2667(18%2930045-8.pdf). Once undernourished, the body-mass index (BMI) of Britain’s poorest children has been shooting up, revealing a profound socioeconomic inequality in health.

“What this shows is the dramatic impact the environment has had,” said Professor Rebecca Hardy, one of the team of researchers at University College London whose [longitudinal study](http://www.thelancet.com/pdfs/journals/lanpub/PIIS2468-2667(18%2930045-8.pdf) exposed these stark results.

“From the 1980s, we’ve increasingly had an environment that encourages an unhealthy diet and discourages physical activity,” Hardy said. “It’s much harder to make healthy choices.”

A dramatic reversal

Published in The Lancet Public Health, [the UCL research](http://www.thelancet.com/pdfs/journals/lanpub/PIIS2468-2667(18%2930045-8.pdf) used data from four cohorts of British children, born in 1946, 1958, 1970 and 2001. The study compared how their weight, height and BMI changed over time.

The data showed that in the first three cohorts, there was little evidence of the impact of socioeconomic inequality on average BMI. For the 2001 group, though, children from poorer backgrounds proved to be much [more likely to be overweight](http://www.thelancet.com/pdfs/journals/lanpub/PIIS2468-2667(18%2930045-8.pdf).

Meanwhile, they had largely caught up to richer children in height. In 1953, just before food rationing ended in Britain, the country’s poorest seven-year-olds were a whole [3.9 centimetres (cm) shorter](http://www.thelancet.com/pdfs/journals/lanpub/PIIS2468-2667(18%2930045-8.pdf) than the richest kids. By 2008 this [gap had shrunk](http://www.thelancet.com/pdfs/journals/lanpub/PIIS2468-2667(18%2930045-8.pdf) to just 1.2 cm.

“The millennium cohort was born into this much more obesogenic environment, and so the inequalities are there from very early on,” said Hardy. “Whereas the 1970s cohort hit this environment a bit later in their teenage years: that’s when you see the inequalities start to emerge.”

"Once somebody becomes overweight or obese, it’s difficult to change that trajectory"

The study also adds further weight to concerns that health inequalities at a young age have a substantial impact on adult life, which means early intervention is particularly important. The obesity epidemic is widespread, but a particular problem in poor families.

“Social inequalities do increase into adulthood, so if the current cohorts of children follow that, things are going to get worse,” said Hardy. “Once somebody becomes overweight or obese, it’s difficult to change that trajectory.”

What can be done?

“What we’ve done before hasn’t been good enough, we can see that,” said Hardy. “We need some more radical policies put in place.”

One of these radical policies is the sugar tax coming into force in April 2018 in the UK. Interestingly, a whole year before coming into effect, Coca Cola dramatically cut the sugar content of its drinks. And evidence from other countries suggests this tax could have a big impact.

“There is an example from Mexico,” said Hardy, “where they introduced an excise tax on sugar-sweetened drinks, and there was evidence that this reduced purchase of the taxed drinks within the first 12 months.”

Public Health England recently found that overweight or obese boys and girls consume up to 500 and 290 calories too many each day. Pointing out that the NHS spends around £6 billion ($8.5 billion) a year treating obesity-related conditions, they have challenged the food industry to reduce calories in products consumed by families by 20% by 2024.

“We need to carry on tracking the body size of children to see if these things actually work”

“We know that targeting the individual or the families with messages hasn’t seemed to work,” said Hardy, “because we’ve seen an increase in obesity over this period.” Instead, she recommends more “upstream”, high-level policies which change children’s environments: such as the sugar tax, initiatives within the school system, and preventing supermarkets from promoting bad food to kids.

“If these policies are put in place,” she pointed out, “we need to carry on tracking the body size of children to see if these things actually work.” By building data tracking into policies from the start, they can be refined or discontinued if they’re unsuccessful. And in the long term, these efforts can build a rich body of data to inform future policies.

By painting the picture of profound changes in the size of Britain’s children, the UCL team have shown that, without effective interventions in preventing obesity, these socioeconomic inequalities will persist.

“The whole of society needs policies and changes to the environment in place,” said Hardy, “so that everyone is able to make these healthier choices.”

(Picture credit: Flickr/USDA)