Study highlights individual and combined effect of obesity on asthma development

Belly fat, known clinically as central obesity, has been linked to the development of asthma in a new study.

The findings, which will be presented at the European Respiratory Society's Annual Congress in Amsterdam today (25 September 2011), have shown central obesity as a risk factor for the disease.

Excess abdominal fat has been linked with a number of health effects, such as diabetes and heart disease, but there has been little focus on its link with lung disease.

Previous studies have found a link between asthma and body mass index (BMI), which is a marker for overall obesity. This new study looked at waist circumference, which is a marker for central obesity, to see whether this form of obesity could also contribute to asthma risk. The research is one of the first prospective studies to investigate the individual and combined effect of central and overall obesity on incident asthma in adults.

Researchers followed 23,245 adults without asthma, aged 19-55 years from the second Norwegian Nord-Trondelag Health Study (HUNT), for 11 years. The participants had their BMI measured along with their waist circumference to test overall obesity and central obesity, respectively. They were also asked to report incidence of asthma.

The results showed that people who were centrally obese but not overall obese were 1.44-times more likely to develop asthma. Additionally, people who were both centrally obese and obese overall were 1.81-times more likely to develop asthma.

Ben Brumpton, from the Norwegian University of Science and Technology, said: "Asthma can affect people of all sizes, but our study has highlighted both the individual and combined effect of central obesity and overall obesity on asthma development. Both these measures have an individual impact on asthma and an additive effect when they are combined.

It is not yet clear why this association exists. Central obesity is closely associated with insulin resistance and metabolic syndrome. These factors may play important roles concerning central obesity-related asthma. We will evaluate the effects of these factors on the development of asthma in future studies."