29th June 2011 - Women who have never smoked are at greater risk of being overweight or obese than those who do, according to researchers, who say they are also more likely to be die early of illnesses associated with obesity.
The Scottish study also suggests that higher smoking rates towards the end of the last century may have suppressed obesity levels.
The findings come from an investigation by Dr Laurence Gruer OBE, Director of Public Health Science at NHS Health Scotland, who set out to examine the relationship between causes of death, social position, and obesity in women who had never smoked.
Data was examined from 3,613 non-smoking women in west central Scotland who had been enrolled in the Renfrew and Paisley study in the early 1970s.
Gruer and colleagues grouped the participants - who were aged between 45 and 64 when recruited - by occupational class and by body mass index (normal weight, overweight, moderately obese and severely obese). Over a 28 year period half the women died, including 916 (51%) from diseases of the heart and circulation and 487 (27%) from cancer.
Obesity and deprivation
The researchers found that women in the lower occupational groups were more likely to die of diseases of the heart and circulation, but not cancer. They were also more likely to be severely obese, which was associated with the highest death rates.
The authors also found that, compared with the smokers, women who never smoked were much more likely to be overweight or obese. "Overweight and obesity were more prevalent among never smokers than among current smokers in all occupational classes and among both never smokers and smokers in the lower occupational classes," they write.
They also conclude that being overweight and obese were already common traits among women taking part in the study more than 35 years ago, with the "true extent concealed by the high smoking rates in the population as a whole". They add that this suggests that "the decline in smoking rates in recent decades may have contributed to the increase in overweight and obesity".
The authors make clear that a history of lifelong smoking is more likely to lead to death than obesity, but that being overweight or obese brings an increased risk of conditions such as diabetes, high blood pressure and arthritis that are likely to be a burden on health and social services in more disadvantaged areas of the country.
The research appears in the online edition of the British Medical Journal. In an accompanying editorial, Professor Johan Mackenbach from the Erasmus Medical Center in Rotterdam, comments: "Exchanging smoking for obesity is a good bargain, but inequalities in mortality will not necessarily become smaller.
"Inequalities in mortality persist among those who have never smoked, partly because obesity takes over the role of smoking, but they persist at a much lower level, and that is good news for whoever wants to reduce health inequalities."
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