Overweight children have lower intelligence and are more likely to be depressed, controversial research shows

Overweight children are less intelligent than their slimmer peers, according to controversial research.

Scientists in the US, who followed more than 5,000 nine- to 11-year-olds, found that students with a higher body mass index (BMI) performed worse on tests.

And they were also more likely to have symptoms of depression, researchers said.

But it’s not clear whether a poor diet harms brain development or whether an underdeveloped brain causes overeating.

Experts have long warned that a ‘quick fix’ environment, combining unhealthy diets with increasingly sedentary lifestyles, has caused problems in the way children develop.

Previous studies have also suggested that BMI is associated with changes in the development of the brain’s prefrontal cortex. Deficits in working memory can contribute to poor nutritional decisions.

The researchers from Washington University in St. Louis, Missouri reviewed data from more than 2,500 girls and 2,700 boys between 2016 and 2018.

Over a two-year follow-up, they found that children who scored one point lower on imagery and vocabulary tasks had, on average, a higher BMI of 0.012 (1.6 percent).

Overweight or obese children – who had a BMI above the 85th percentile – were almost twice as likely to have “more problems annually than children of normal weight”, scientists said.

Writing in the diary JAMA PediatricsAccording to researchers, the findings highlight the “importance of cognitive and mental health” for weight gain.

They also called on doctors to monitor children who are overweight or obese “for increased depression problems.”

Future research could investigate why this is the case and why some people do not adhere to a healthy diet or lifestyle.

Experts have long warned that changes in children’s diets and a lack of physical activity have created ‘the perfect storm’ in stunting children’s development.

Professor Iain Buchan, a public health expert from the University of Liverpool, told MailOnline: ‘If you look at the change in our energy balance, the way we eat, what we eat, the way we move and interact with each other, all these things have changed dramatically over the past twenty years.

‘Although we are more connected, we are also more sedentary, because everything happens while sitting, online or fixed to a device.

‘Our bodies did not evolve to use so little energy. We have to move around and interact physically and spend time disconnected to think.”

He added: ‘Life has changed so much in terms of pace and food has changed too: we now have unhealthy diets, with junk food high in fat, salt and sugar that provides quick energy, which is not good for the health.

“We have created a quick-fix environment that revolves around short-term pleasure and causes long-term pain.

‘It’s the perfect storm, to combine that with being fixated on place and a lack of physical interaction – all these things cause problems with the way children develop. It’s not what our bodies evolved to do.

‘These problems have been ingrained in a generation and we are now seeing the consequences.

“We’re seeing an increase in mental health issues, obesity and other diseases, and drug use.”

The pressures of modern life have long been blamed for contributing to what has been widely described as a ‘crisis’ in children’s mental health.

Nearly a quarter of children in England now have a ‘probable mental disorder’, a report from the Office of National Statistics (ONS) has found.

The number of these disorders, registered on the basis of answers to a questionnaire among eight to sixteen year olds, is increasing.

Data for 2023 shows that 23.3 percent of children are likely to have a mental health disorder such as anxiety or depression, compared to 19 percent the year before.

Experts have also previously highlighted the impact of the Covid pandemic, and the disruption it has caused to children’s education and social lives, in addition to the cost of living crisis and social media, which is detrimental to the mental well-being of children.

The latest data on childhood obesity in England also shows that one in ten children are overweight by the time they start primary school, rising to around one in four by the sixth year.

Obesity is taking a huge financial toll in Britain, with consequent health consequences in terms of lost working years, healthcare costs and the price of NHS treatments, costing the economy an estimated £100 billion a year.

Experts have pointed to a lack of exercise and a poor diet high in ultra-processed foods as major causes of Britain’s childhood obesity epidemic.