Children with ADHD are more likely to become obese teenagers, a new study has found.

ADHD (attention deficit hyperactivity disorder) is a behavioural disorder, the main symptoms of which include inattention, impulsivity and hyperactivity. Those affected show poor concentration, are often unable to complete tasks, day dream a lot, are distracted easily, act without thinking and can suffer temper tantrums. Around one in every 20 children is affected.

According to UK scientists, while previous research has indicated a link between ADHD and obesity, the reason for this was unclear. They decided to investigate further by following children through to adolescence.

They monitored the progress of almost 7,000 children in Finland. All were assessed for ADHD at the ages of eight and 16. Their body mass index (BMI) and body measurements, such as hip and waist measurements, were also recorded at these ages.

The study found that children who had symptoms of ADHD at the age of eight were significantly more likely to be obese at the age of 16. These children were also much more likely to lead a sedentary lifestyle.

According to the study's lead author, Prof Alina Rodriguez, while obesity is a growing problem in all children and young people, ‘these findings suggest that it's particularly important for children with ADHD'.

"It appears that lack of physical activity might be a key factor. We think encouraging children with ADHD to be more physically active could improve their behaviour problems as well as helping them to stay a healthy weight, and studies should be carried out to test this theory," she said.

The scientists from Imperial College London also assessed whether binge eating may have a role in the findings, but found that this kind of behaviour was no more prevalent among children with ADHD.

Details of these findings are published in the Journal of the American Academy of Child and Adolescent Psychiatry.