FRIDAY, Sept. 17 (HealthDay News) -- A poor diet and lack of exercise can cause an imbalance in metabolism that may increase a child's risk of developing asthma, a new study suggests.

This is true even among children with a healthy weight, a finding that challenges the widespread belief that obesity itself is a risk factor for asthma, according to the study authors.

The researchers analyzed data from nearly 18,000 children, aged 4 to 12 years, who were taking part in the Coronary Artery Risk Detection in Appalachian Communities (CARDIAC) project.

The research team focused on a set of markers for early metabolic problems, including triglyceride (a type of blood fat) levels and evidence of acanthosis nigricans, raised patches of tan to brown skin that are often biomarkers for insulin resistance and excess levels of insulin in the blood.

After they controlled for a number of factors, the researchers concluded that asthma prevalence among the children was strongly associated with triglyceride levels and the presence of the skin disorder acanthosis nigricans, independent of body mass index.

The study findings were released online in advance of publication in an upcoming print issue of the American Journal of Respiratory and Critical Care Medicine.

"Our research showed that early abnormalities in lipid and/or glucose metabolism may be associated to the development of asthma in childhood," lead author Dr. Giovanni Piedimonte, a professor and chairman of the pediatrics department at West Virginia University School of Medicine, physician-in-chief at WVU Children's Hospital, and director of WVU's Pediatric Research Institute, said in an American Thoracic Society news release.

"Our findings also imply a strong and direct influence of metabolic pathways on the immune mechanisms, both innate and adaptive, involved in the [step-by-step disease development] of asthma in children," he added.

More information

The American Lung Association has more about children and asthma.