Wednesday, March 4, 2015

Smoking Cessation: Minimal Impact on Weight

The association of tobacco use and body weight has long been a matter of concern.  In 2004, I collaborated with Swedish investigators to publish the first research on whether switching from cigarettes to smokeless tobacco blunts some of the weight gain normally seen with quitting via abstinence (abstract here, blog post here). 

We found that Swedish snus users and smokers who switched to snus gained no more weight than nonusers (average gain of around 7 pounds over 9 years).  In contrast, the big gainers in our study were smokers and snus users who completely abstained from nicotine and tobacco.

Numerous studies have documented that smokers weigh less than nonsmokers, and smokers who quit add pounds.  Since the 1970s, there are fewer smokers and more former smokers in the U.S.  For example, in 2010, only 19% of the adult population were current smokers (44 million), while 22% (49 million) were former smokers.  Did changes in population smoking contribute significantly to changes in population overweight and obesity?  The answer is no.

My University of Louisville colleague, research economist Nantaporn Plurphanswat, and I explore this question in a research article published in BMC Obesity (available here).  We used data from the National Health and Nutrition Examination Surveys (NHANES) for the years 1999 through 2012. 

Our analysis used body mass index (BMI), a measure of weight that accounts for height.  Conventional BMI categories are underweight (BMI < 18.5), normal weight (18.5 to less than 25), overweight (25 to less than 30) and obese (30+).

Consistent with previous studies, we found that smoking was associated with lower BMI among both men and women.  In addition, being a smoker increased the probability of being normal weight by 12% and reduced the probability of being obese by 13% among men; the magnitudes for women were smaller, +7%  for normal weight and -8% for obesity.

We noted that women with higher education had significantly lower BMI than those with less education; this relationship was not seen among men.  Marriage was associated with higher BMI among men, but lower BMI among women.

In a positive finding for men, we found no difference between never smokers and former smokers in terms of being in particular BMI categories.  However, women were shown to be more prone to weight gain.  Women who were former smokers had lower probability of underweight (0.2%), normal weight (2.3%), and overweight (0.4%), but had higher probability of obesity (2.9%). 

No one should be dissuaded from quitting cigarettes, especially when there are many smoke-free options like snus and e-cigarettes that might obviate any weight gain.

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