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Obese vs. Non-Obese

Louis-Philippe Boulet MD, FCCP, FRCPC
Laval University Heart & Lung Institute
Québec, OC, Canada


Dr. Louis-Philippe Boulet, MD
Laval University Heart & Lung Institute

An increased prevalence of asthma has been reported in obese subjects, both in adults and children, and particularly in women. In most instances, obesity precedes the development of asthma. However, the mechanisms by which obesity could influence the development of asthma are still uncertain. Various contributing factors have been suggested, such as an alteration in lung function from obesity-related mechanical changes, inflammatory, hormonal or neurogenic mechanisms, an increased prevalence of co-morbid conditions, or common genetic or developmental influences. The possibility of asthma over-diagnosis due to the presence of asthma-like symptoms in the obese has also been suggested but recent evidence suggests that this does not explain the increased prevalence of asthma in subjects with increased Body Mass Index (BMI). It is still unclear if the risk of developing asthma in the obese is related to an increased prevalence of allergic sensitization, or if the pattern of body fat distribution influences the prevalence of associated asthma. Obesity is associated with systemic inflammation and oxidative stress but how these could possibly translate into changes in airway function is uncertain. Furthermore, changes in adipokines serum levels, such as increases in serum leptin and reductions in adiponectin are found in obese asthmatic patients but these changes seem more related to obesity per se than to asthma. Furthermore, although many animal and human studies suggest a positive association between BMI and airway hyperresponsiveness, this has been challenged. An increasing number of studies, however, show that asthma is more difficult to control in the obese, possibly due to a change in its phenotype, associated with a less eosinophilic airway inflammation, a reduced response to asthma medications, or to other contributing factors. Obesity or weight gain are associated with an increased health-care utilization and poorer asthma-related quality of life. Improvements in asthma-related clinical/inflammatory parameters seem less in the obese than in the non-obese following inhaled corticosteroids, and although reports suggest that response to leukotriene antagonists is less influenced by obesity, additional studies are needed to determine what could be the optimal pharmacological treatment of asthma in the obese. Otherwise, in those with increased BMI, weight reduction has led to a universal improvement of asthma symptoms and a reduction in medication needs. More research is needed to determine the link between asthma and obesity and the optimal management of asthma in the obese.

Slide Presentation
Posted: March 2010

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