A study published in the journal CHEST compared various measurements among 44 obese individuals with asthma and 44 non-obese individuals with asthma. The obese individuals with asthma seem to carry or bear a specific trait or phenotype that causes them to poorly manage asthma. The data which were measured by researchers from Quebec, Canada include: pulmonary changes, methacholine challenge scores, sputum induction cell counts, symptom perceptions, BMI/waist circumference, and waist-to-hip ratio. Compared to the non-obese subjects, the obese subjects showed poorer asthma management, lower total lung capacity, lower expiratory reserve volume, lower functional residual capacity, and lower residual volume. Blood levels of C-reactive protein as well as fibrinogen were higher in the obese subjects. Bronchial and systemic inflammatory characteristics of pulmonary function changes suggest that obese individuals may actually carry a different phenotype of asthma.

Obesity has been found to be a causative factor for low grade inflammation and cytokine dysfunction. Inflammation is linked to autoimmune responses and may play a role in pulmonary function similar to other obesity related disorders. Morbidly obese children and adults both experience a higher risk for sleep apnea; a potentially deadly pulmonary disorder. The research further supports the belief that obesity needs to be managed aggressively to minimize the negative health consequences associated with carrying high levels of body-fat. Studies continue to find new ways in which obesity is linked with other disease states (co-morbidities) or the negative impact upon other diseases. With regard to asthma this specific study concluded that individuals who maintain a normal, ideal bodyweight will likely experience improvements in the management of their asthma. Asthmatics that exercise often improve their disease management to higher levels. (CHEST, 2009).