Children and adolescents who are overweight or obese may be more likely to develop asthma, according to a study in the US.
The researchers said in the journal Pediatrics that research has long been linked between obesity and asthma in adults, but provides conflicting evidence for this for young people.
The current study followed more than 500,000 children between the ages of two and 17 years, an average of four years. The result is that around 8 percent of these children suffer from asthma.
The study found that overweight children were 17 percent more likely to suffer from asthma than healthy weight children.
Young obese people are 26 percent more likely to develop asthma.
When researchers looked at the relationship between asthma and obesity based on a test known as a breathing test, it was clear how easy it was to get air out of the lungs.
The study concluded that obesity was associated with an increased risk of asthma by 29 percent, based on this standard. "Experts believe that abnormal lung growth associated with obesity blocks airflow," said Jason Lang, from Duke University School of Medicine in Durham, northern California, the study's lead author.
He added that obesity can also cause a risk of developing what is known as metabolic heart disease, such as high cholesterol, and the inability to use the hormone insulin to help get energy from blood sugar.