Smokers who are heavily addicted to nicotine are significantly more likely to gain weight when they try to quit, researchers report.
Investigators studying 186 patients who successfully quit smoking after receiving nicotine replacement therapy at an outpatient clinic found that mean body mass index increased significantly from 23.5 kg/m2 at an initial consultation to 23.9 kg/m2 at 3 months after the start of therapy. A high Fagerstrom Test for Nicotine Dependence (FTND) score, indicating severe dependency, was found on multivariate analysis to be the strongest predictor of increase (using a gender-adjusted standardized coefficient).
Dr. Maki Komiyama of Kyoto (Japan) Medical Center and colleagues reported their findings online Aug. 21 in the open access journal PLoS One (PLoS One 2013 Aug. 21 [doi:10.1371/journal.pone.0072010]).
The findings are important because, while smoking cessation is known to reduce cardiovascular and cancer risk and to reduce all-cause mortality, associated weight gain is linked with greater risk of glucose intolerance and a reduction in the beneficial effects that quitting has on pulmonary function. Concerns about weight gain also can lead to a failure to quit smoking, they said.
"Even if one is expected to experience post-cessation weight gain, quitting smoking still leads to a reduced cardiovascular risk. However, there is also a possibility that if one can prevent post-cessation weight gain, then this will further reduce the cardiovascular risk due to having ceased smoking," they wrote.
"Even if one is expected to experience post-cessation weight gain, quitting smoking still leads to a reduced cardiovascular risk"
Thus, they continued, the ability to predict which patients are likely to gain weight during smoking cessation therapy – and performing weight control accordingly at the outset – could lead to improved outcomes, and the findings of this study may be useful for discriminating such patient groups.
Study participants were 132 men and 54 women with a mean age of 59.6 years who visited the smoking cessation clinic at the National Hospital Organization Kyoto Medical Center between July 2007 and November 2011 and successfully quit smoking.
Other factors found on univariate analysis to be significantly associated with BMI increase included triglyceride level, high-density lipoprotein cholesterol, and daily cigarette consumption. "To further investigate ... we performed multivariate analysis. The results demonstrated that the triglyceride level and FTND score were factors determining the post-cessation BMI increase, and that the FTND score was the strongest one," the investigators wrote.
An FTND score of 8 or more (on a scale of 1-10) was associated with larger postcessation BMI increase, and the increase was statistically significant when compared with the level of BMI increase in those with a score of 7 or less, they noted.
"The result that a high FTND score was the most important determinant of a BMI increase supports the hypothesis that post-cessation weight gain is one of the nicotine withdrawal symptoms," they said.
As for the association between triglyceride elevation and weight gain, the mechanism is not clearly understood and requires further study, they noted.
With the exception of two patients who did not receive medical treatment, study participants were treated with either oral varenicline (95 patients) or nicotine patch (89 patients). No difference was seen between the varenicline and nicotine patch groups with respect to BMI increase, but the varenicline group had higher nicotine dependency.
They also noted that, in their study, "although a significant increase in BMI was confirmed after smoking-cessation therapy, the BMI increase was only 0.4 kg/m2 (1.1 kg), which is much smaller than reported in previous studies for people who quit smoking on their own initiative (2.8-3.8 kg)."
Additional study is needed to determine the appropriate timing for initiating interventions against post–smoking cessation weight gain, they noted.
This study was supported by a grant-in-aid for clinical research from the National Hospital Organization and the Pfizer Health Research Foundation. The authors reported that one study drug (varenicline) is manufactured by Pfizer but confirmed "that this does not alter their adherence to all the PLoS One policies on sharing data and materials."