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 nearly all of these studies have used body mass index to identify overweight & obesity, 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 1015 individuals at age 32.
Results: There was a significant association between percent body fat and asthma in women (p = 0.04) but not in men (p = 0.88). Airflow obstruction was associated with percent body fat in women (p = 0.05) but there was an inverse association in men (p = 0.01). Airway inflammation, measured by exhaled nitric oxide, was not associated with body fat in either men (p = 0.54) or women (p = 0.17). Findings were similar after adjusting for current smoking and use of inhaled corticosteroids.
Conclusion: Asthma and airflow obstruction is associated with percent body fat in women but not men. This does not appear to be mediated by airway inflammation.