The effects of diet-induced weight loss on asthma control and quality of life in obese adults with asthma: a randomized controlled trial.

Objective: While the effects of obesity on asthma are yet to be fully clarified, increased fat tissue is known to increase the severity of asthma and to impair asthma control. This study evaluated the effects of diet-induced weight loss on the characteristics of asthma in obese adults with asthma. Methods: A total of 55 obese individuals (BMI >= 30.0) with asthma were enrolled in the study and randomized into the diet or control groups. The anthropometric measurements, asthma control test (ACT) scores, asthma quality of life questionnaire (AQLQ) scores, pulmonary function tests (PFT) and daily food consumption of the participants were recorded and compared at the baseline and at study completion. Results: The changes recorded in body weight (diet -5.2 (4, 5); control, -0.1 (1.3)), ACT score (diet 2.0 (2.0); control 0.0 (1.7)) and AQLQ score (diet 0.8 +/- 0.1; control -0.02 +/- 0.5) of the participants in the diet group were significantly higher than in the control group (p = 0.00). The increases in forced expiratory volume in one second (FEV1) and the forced vital capacity (FVC) measurements of the participants with weight loss of >= 5.0 percent were significant when compared to those with weight loss of <5.0 percent (p < 0.05). While total energy uptake and carbohydrate consumption at the end of study were found to be decreased in the diet group, they had increased in the control group (p < 0.05). Conclusion: Diet intervention improved asthma control and quality of life in obese patients with controlled asthma in this study. However to generalize this finding to all asthma patients, further studies including uncontrolled asthmatics are needed.