From a recent review:
Recent findings: Clinical and epidemiological studies indicate that obese patients with asthma may represent a unique phenotype, which is more difficult to control, less responsive to asthma medications and by that may have higher healthcare utilization. A number of common comorbidities have been linked to both obesity and asthma, and may, therefore, contribute to the obese–asthma phenotype. Furthermore, recently published studies indicate that even a modest weight reduction can improve clinical manifestations and outcome of asthma.
Summary: Compared with normal-weight patients, obese and overweight patients with asthma have poorer asthma control and respond less to corticosteroid therapy. Future studies focusing on the mechanism underlying both obesity and asthma including the obese–asthma phenotype are required to better characterize the link between the conditions and target the management of this patient group.
Of particular interest, the review suggests weight loss as a treatment modality.