Abstract
Background: Several studies have found obesity to be associated with an increased prevalence of asthma. For reasons that remain unclear, this association has often been reported to be stronger in women than men. One possible explanation may be that these studies have used body mass index to identify adiposity, which may be a less reliable measure of body fat in men than women.
Objective: To explore the association between body fat percent measured by bioelectrical impedance analysis, and asthma, airflow obstruction and airway inflammation in men and women.
Methods: Respiratory questionnaires, spirometry, bronchodilator response, exhaled nitric oxide and percent body fat were measured in a population-based cohort of approximately 1000 individuals at age 32.
Results: There was a significant association between percent body fat and asthma in women (p=0.043) but not in men (p=0.75). Airflow obstruction was associated with percent body fat in women (p=0.046) but there was an inverse association in men (p=0.010). Bronchodilator responsiveness was also associated with lower body fat in men (p=0.004). Airway inflammation, measured by exhaled nitric oxide, was not associated with body fat in either women (p=0.17) or men (p=0.25).
Conclusion: Adiposity is associated with asthma and airflow obstruction in women. This does not appear to be mediated by airway inflammation. In men airflow obstruction and bronchodilator responsiveness are associated with a lower percent body fat. Clinical Implication: In women, but not in men, obesity is associated with asthma and airflow obstruction but there was no association with airway inflammation.