Obesity is one of the UK’s fastest-rising health problems. In 2016, 26% of adults were obese, compared with 15% in 1993. Children are affected, too, with 10% of four-year-olds and 20% of 11-year-olds obese. The condition is firmly linked with a variety of other heightened health risks, including type 2 diabetes, coronary heart disease, stroke and some types of cancer.

Now the scientists indicate that if your waistline is growing, your brain could be shrinking. They warn that as people become more obese, their grey matter progressively shrinks. The finding reinforces growing evidence that obesity has a damaging effect on intelligence. The new research is based on brain scans of nearly 10,000 Britons aged 47-62. Some brain regions were particularly strongly affected, said the co-authors Mark Hamer, professor of exercise medicine at Loughborough University, and David Batty, professor of epidemiology at University College London.

In separate research, also just published, Batty and his colleagues calculated how obesity accelerates the onset of illnesses as people age. The study of 120,000 people in Europe, published in The Lancet, found that severely obese men and women were hit by illnesses such as heart disease and strokes seven years earlier than people of normal weight. The mildly obese were hit by such diseases three to four years earlier.