Overweight children are just as likely as thin children to have celiac disease, a new study confirms.

It's a common misconception - even among many doctors - that celiac disease is limited to people who are underweight.

“Being overweight certainly does not exclude the diagnosis, as this paper shows,” said Dr. Peter Green, director of the Celiac Disease Center at Columbia University Medical Center in New York City, who was not involved in the new study.

Between 0.5 percent and 1 percent of people living in the developed world are thought to have celiac disease, in which gluten in food triggers a damaging immune response in the small intestines.

Patients with celiac disease often, but not always, have diarrhea. They also have trouble absorbing nutrients from food.

To find out the prevalence of celiac disease among overweight and obese children, Dr. Raffaella Nenna and colleagues used data collected at a nutrition center at the University of Rome between 1998 and 2003, from 1,527 overweight and obese children and young adults between the ages of two and about 24 years.

Seventeen children, or about 1 percent, tested positive for celiac disease through blood work and damage to their small intestines, the authors reported in the Journal of Pediatric Gastroenterology and Nutrition.

Those who tested positive for celiac disease were invited to start a nutritionally-balanced gluten-free diet, according to the researchers.

The children who had symptoms of celiac disease reported improvement once they started the gluten-free diet. They also tended to lose weight.

“There are two things when you go on a gluten free diet,” said Green. “You need to learn what to avoid and what to eat. Patients will often get information on how to make a gluten-free diet a healthy diet.”

He added that people with celiac disease are encouraged to see a nutrition specialist when starting a gluten-free diet so they don’t just replace what they’re currently eating with junk food.

Green also said it’s important that people – including doctors – don’t discount a person’s potential celiac symptoms based on appearance.

“The clinical manifestations are very diverse,” he said. “Physicians just looking at a patient can’t say they couldn’t have it if they’re overweight or tall.”