NEW YORK (Reuters) -- The weight gain that commonly occurs after stopping smoking can negatively affect lung function, particularly in men, according to researchers.
But the health benefits of quitting smoking still far outweigh any negative effects of weight gain, the researchers emphasize in their report, published in the current issue of the American Journal of Respiratory and Critical Care Medicine.
The study, led by Dr. Robert A. Wise of Johns Hopkins University School of Medicine in Baltimore, Maryland, followed more than 5,000 adults from 10 US and Canadian communities for 5 years. Two thirds of the participants completed an intensive smoking cessation program; the rest received routine medical care and served as a comparison group.
About 20% of those who tried to quit were successful. The ex-smokers gained an average of 5 kg (11 pounds) in the first year after quitting, and more than one-third added over 10 kg, with women gaining more overall than men.
The researchers found that measures of lung function declined with increasing body weight, more so for men than for women. This may be because men tend to add pounds around the abdomen, which could hinder lung function more than extra padding on the hips and thighs as commonly seen in women, the researchers suggest.
The effect of weight gain, however, is small in comparison with the effect of continued smoking on pulmonary function. A person who quit smoking would have to gain about 60 kg (132 pounds) to have the same negative effects on the lungs as he or she would cause by continuing to smoke, say the research team.
"Because excessive weight gain occurs in the first year after cessation, it tends to have a 'one-time' effect on lung function. In contrast, continuing to smoke causes persistently greater decline in lung function," they write.
The study results do underline the need to pay particular attention to nutrition and weight during a cessation program, especially for men and for long-time smokers whose lungs have already been impaired by years of exposure, the researchers conclude.
SOURCE: American Journal of Respiratory and Critical Care Medicine (1998;157:866-872)
