A new study has found that children who are obese are at a much greater risk of immediate health problems than previously thought.

According to US scientists, most research in this area has focused on the long-term consequences of childhood obesity. However their study has shown that just as much concern should be focused on the immediate consequences.

"This study paints a comprehensive picture of childhood obesity, and we were surprised to see just how many conditions were associated with it," said lead author, Dr Neal Halfon, of the University of California in Los Angeles.

The study involved over 43,000 children aged between 10 and 17. Of these, 15% were overweight and 16% were obese.

It found that compared to healthy weight children, obese children are almost twice as likely to develop three or more medical, developmental or mental health problems. Overweight children also have an increased risk, but not to the same degree.

In fact overall, obese children were more likely to report, among other things, poorer general health, more disability, more problems with school, higher levels of ADHD (attention deficit hyperactivity disorder), higher levels of depression, more developmental delays, more bone and joint problems, higher levels of asthma and more headaches.

"The findings should serve as a wake-up call to physicians, parents and teachers, who should be better informed of the risk for other health conditions associated with childhood obesity, so that they can target interventions that can result in better health outcomes," Dr Halfon said.

Details of these findings are published in the journal, Academic Pediatrics.