Immediate and long term effects of weight reduction in obese people with asthma: randomised controlled study.
To investigate the influence of weight reduction on obese patients with asthma. Design: Open study, two randomised parallel groups.
                Private outpatients centre, Helsinki, Finland.
                Two groups of 19 obese patients with asthma (body mass index (kg/m(2)) 30 to 42) recruited through newspaper advertisements.
                Supervised weight reduction programme including 8 week very low energy diet.
                Body weight, morning peak expiratory flow (PEF), forced vital capacity (FVC), forced expiratory volume in one second (FEV(1)); and also asthma symptoms, number of acute episodes, courses of oral steroids, health status (quality of life).
                At the end of the weight reducing programme, the participants in the treatment group had lost a mean of 14.5% of their pretreatment weight, the controls 0.3%. The corresponding figures after one year were 11.3% and a weight gain of 2.2%. After the 8 week dieting period the difference in changes in percentage of predicted FEV(1) from baseline in the treatment and control groups was 7.2% (95% confidence interval 1.9% to 12.5%, P=0. 009). The corresponding difference in the changes in FVC was 8.6% (4. 8% to 12.5%, P<0.0001). After one year the differences in the changes in the two groups were still significant: 7.6% for FEV(1) (1. 5% to 13.8%, P=0.02) and 7.6% for FVC (3.5% to 11.8%, P=0.001). By the end of the weight reduction programme, reduction in dyspnoea was 13 mm (on a visual analogue scale 0 mm to 100 mm) in the treatment group and 1 mm in the control group (P=0.02). The reduction of rescue medication was 1.2 and 0.1 doses respectively (P=0.03). After one year the differences in the changes between the two groups were -12 for symptom scores (range -1 to -22, P=0.04) and -10 for total scores (-18 to -1, P=0.02). The median number of exacerbations in the treatment group was 1 (0-4) and in the controls 4 (0-7), P=0.001.
                Weight reduction in obese patients with asthma improves lung function, symptoms, morbidity, and health status.
There is currently a very small amount of evidence assessing the effects of dietary interventions intended as part of a wide-ranging weight-loss programme. Whilst we are unable to recommend these strategies as concomitant interventions with drug-based therapy for the specific management of asthma, dietary interventions such as weight-loss programmes may provide benefits in specific patients. However, the impact of a calorie-controlled diet on the signs and symptoms of asthma in the general asthmatic population is yet to be established.