Tuesday, March 03, 2009
While smoking has an obvious detrimental effect on health and longevity, some individuals are known to take up the practice in order to lose weight, while those who are current smokers are hesitant to quit for fear of gaining weight.
Indeed, some reports suggest that adolescent girls who are trying to lose weight are twice as likely to be smokers as girls who are not attempting to lose weight.
Additionally, it has been shown that cessation of smoking on average results in an increase of body weight of 2.8 kg in men and 3.8 kg in women. Further, a total of 10% of men and 13% of women who quit smoking may gain in excess of 13kg.
Given the interplay between excess weight and smoking, an interesting question recently addressed by an article in the British Medical Journal is which of these factors, smoking or obesity, are more important with regards to risk of death.
The study used nationwide conscription data on 45 920 Swedish men who performed mandatory military conscription tests at approximately 18 years of age back in 1969-70. Some 38 years later the authors investigated who of these men had since died, and the relationship between their weight and smoking status and conscription and their subsequent likelihood of mortality.
In comparison to normal weight men (BMI = 18.5-24.9 kg/m2) obese (BMI >30.0 kg/m2) men had more than double the risk of dying, while overweight (BMI = 25.0-29.9 kg/m2) men had a 33% greater chance – even after smoking status was accounted for in the analyses.
Secondly, in comparison to non-smokers, heavy smokers (>10 cigarettes/day) had more than double the mortality risk, while light smokers (1-10/day) had a 54% higher chance – even after weight status was accounted for in the analyses.
When looking at the combined effect of smoking and weight status on mortality, it became apparent that both have a similarly detrimental effect on longevity. That is, normal weight/light smokers have the same risk of death as overweight/non-smokers, while normal weight/heavy smokers have approximately the same risk of death as obese/non-smokers.
Predictably, worst off were men who were both obese and heavy smokers who, in comparison to normal weight non smokers, had almost a 5-fold risk of dying.
So there you have it – smoking and carrying excess weight are equally likely to kill you.
On a grander scale, in order to establish the true importance of these two risk factors on mortality rates in a given country, the prevalence of both smoking and obesity must be considered. In the recent Canadian past, while obesity rates have been on a steady climb, smoking rates, particularly among adolescents, have been on a severe decline (from 14% in 2001 to 8% in 2005) – likely due to the strong anti-tobacco movement. Thus, it would appear that the time has come for the government to step up and do for obesity rates what has shown to be so successful for smoking rates.
(Thanks to loyal Obesity Panacea follower, Ian Kudryk for drawing my attention to the article)
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