Controlling a person’s weight after they have given up smoking could help maximise the benefits for their lungs

Controlling a person’s weight after they have given up smoking could help maximise the benefits for their lungs, suggests a study in this week’s issue of The Lancet.

Lung function normally declines with advancing age, and smoking causes premature onset and acceleration of this age-related decline. Stopping smoking is beneficial for lung function but may lead to weight gain. Previous studies have reported the effects of quitting smoking and weight change on lung function, but the total effect has not been reported in a general population study.

Susan Chinn (King’s College London, UK) and colleagues sent detailed questionnaires about smoking history to around 6600 people from 27 countries, taking part in the European Community Respiratory Health Survey (ECRHS). Participants had lung function measured in 1991–93, when aged 20–44 years, and in 1998–2002 as part of ECRHS. Smokers had a greater decline in lung function than those who never smoked, and quitters and sustained quitters had a lower rate of decline. During follow-up mean weight and body mass index (BMI) increased in men and women. The increase in weight was greatest in recent quitters and smallest in people who quit and restarted. The effect of increasing weight or BMI on decline in lung function was substantially greater in men than in women, diminishing the benefit of quitting by 38% in men, and 17% in women.

Professor Chinn states: “Our data suggest that quitting smoking is beneficial for lung health, but weight gain is an important factor in reducing the beneficial effects of quitting on lung function in men, and that interventions to reduce this weight gain might be warranted.”

In an accompanying CommentGraham Colditz (Brigham and Womens’ Hospital and Harvard Medical School, Boston, USA) states: “Chinn and colleagues’ findings are important. The results draw attention to the fact that acceleration of decline in lung function must be added to the long list of negative health-consequences of smoking. The survey shows that slowing of lung decline is an added benefit of quitting. The findings highlight the potential for even greater health benefit if weight gain could be prevented after smoking cessation.”