Effects of Weight Loss on Airway Responsiveness in Obese Adults With Asthma

BACKGROUND: The growing epidemics of obesity and asthma are major public health concerns. Although asthma-obesity links are widely studied, the effects of weight loss on asthma severity measured by airway hyperresponsiveness (AHR) have received limited attention. The main study objective was to examine whether weight reduction reduces asthma severity in obese adults with asthma. METHODS: In a prospective, controlled, parallel-group study, we followed 22 obese participants with asthma aged 18 to 75 years with a BMI >= 32.5 kg/m(2) and AHR (provocative concentration of methacholine causing a 20% fall in FEV1 [PC20] < 16 mg/mL). Sixteen participants followed a behavioral weight reduction program for 3 months, and six served as control subjects. The primary outcome was change in AHR over 3 months. Changes in lung function, asthma control, and quality of life were secondary outcomes. RESULTS: At study entry, participant mean +/- SD age was 44 +/- 9 years, 95% were women, and mean BMI was 45.7 +/- 9.2 kg/m(2). Aft er 3 months, mean weight loss was 16.5 +/- 9.9 kg in the intervention group, and the control group had a mean weight gain of 0.6 +/- 2.6 kg. There were significant improvements in PC20 (P = .009), FEV1 (P = .009), FVC (P = .010), asthma control (P < .001), and asthma quality of life (P = .003) in the intervention group, but these parameters remained unchanged in the control group. Physical activity levels also increased significantly in the intervention group but not in the control group. CONCLUSIONS: Weight loss in obese adults with asthma can improve asthma severity, AHR, asthma control, lung function, and quality of life. These findings support the need to actively pursue healthy weight-loss measures in this population.