Central obesity, also known as belly fat, is a new risk factor for asthma, according to findings reported last Sunday at the European Respiratory Societyâ€™s Annual Congress in Amsterdam.
In the abstract, presented by researchers from the Norwegian University of Science and Technology in Trondheim, and the University of Ottawa, Ontario, Canada, they state, â€œCentral obesity in the absence of overall obesity was significantly associated with incident asthma.â€ This means that people with belly fat, who are otherwise not necessarily obese are at risk for asthma.
For purposes of the study, officially known as the second Norwegian Nord-Trondelag Health Study (HUNT), central obesity was defined as â‰¥88cm in women and â‰¥102cm in men, while overall obesity was defined as BMI â‰¥30 kg/m2.
Measures of body mass index (BMI) (which looks at overall obesity) and waist circumference (WC)Â (which defines central obesity) were taken from 23,245 adults who did not have asthma at the start of the study. Eleven years later, with the results adjusted for age, smoking status, family history, physical activity, education, social benefit, gender, and economical difficulty, 3.5% (n=818) had asthma, which correlated with central obesity. Study participants who were centrally obese but not overall obese were 1.44 times more likely to develop asthma, which those who were both centrally and overall obese were 1.81 times more likely to report incident asthma. The people who were overall obese, yet not centrally obese had an odds ratio of 1.38.
Previous studies have found links between asthma and BMI, but this was the first study to specifically look at waist circumference. Itâ€™s interesting to note that this is also one of the first studies to delve into the individual and combined effect of central (WC) and overall (BMI) obesity on incident asthma in adults.
According to Ben Brumpton, one of the researchers from the Norwegian University of Science and Technology, â€œAsthma 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.â€
More studies will be necessary to determine why this association exists. The link between insulin resistance, metabolic syndrome and central obesity is already established, and these factors may be relevant to the factors involved in central obesity-related asthma. In addition, as these studies were only done with adults, it will be quite interesting to discover if the same link exists for centrally obese children.
Source: Respiratory epidemiology: comorbidity. Findings presented Sep. 25, 2011 at the 2011 European Respiratory Societyâ€™s Annual Congress in Amsterdam.