Cigarette smoking increases your heart rate, narrows the walls of your blood vessels and reduces the amount of oxygen being delivered to your system, among other things. That's why smoking is considered a major risk factor for cardiovascular disease.
Unfortunately, obesity is also a risk factor for cardiovascular disease. And most smokers gain between 6 and 13 pounds in the six months after they quit, according to a new study published in the Journal of the American Medical Association.
The benefits of quitting smoking are well known. "Cigarette smoking has short- and long-term cardiovascular effects that are reversible shortly after cessation," according to the study authors.
But the researchers wanted to know if the weight gain following smoking cessation would counteract the positive effects quitting has on your cardiovascular system.
The researchers analyzed data from the Framingham Offspring Study, which included more than 3,200 people. Information from the study participants was collected every four years between 1984 and 2011.
For the current study, researchers first divided up the 27 years of data into four "mini-studies," explained lead author Carole Clair in an email. Each mini study had a time span of about 6 years. The researchers then recorded the participants' weight at the beginning and end of each mini study, and classified the participants into one of four categories: smoker, recent quitter, long-term quitter or non-smoker.
Because the data they used was collected every four years, the researchers didn't know exactly when their study participants' quit smoking, Clair said. So a recent quitter was defined as someone who reported smoking at one data collection point and not at the next. A long-term quitter was someone who reported not smoking at two consecutive data collection points.
The researchers then looked at each mini study to see if participants had a "CVD event," such as coronary heart disease, angina, stroke or congestive heart failure.
The median weight gain for recent quitters over a four-year period was about 6 pounds. Despite this, researchers found quitters had a significantly reduced risk of cardiovascular disease.
Recent smokers who quit were about 53 percent less likely to have cardiovascular disease than those who continued to smoke, Clair said. Long-term quitters had a 54 percent lower risk, despite weight gain.
These results applied to only those in the study without diabetes. While the researchers also looked at data for people WITH diabetes, they did not find a significant association between quitting smoking and a reduced risk of cardiovascular disease. Clair believes the study sample was too small and that more people would reveal results similar to the non-diabetic results.
The smoking data in the Framingham study was self-reported, so participants' could have fudged the truth on their smoking habits. And as mentioned earlier, the exact time period for when participants' quit smoking was undetermined.
The study also did not capture any relapses that the smokers may have had. "Smokers generally need several attempts before successfully quitting," the study authors wrote.
One other limitation to the study is its lack of diversity -- the majority of the participants were white, so the authors aren't sure if their results would translate to a wider population.
People who quit smoking can reduce their risk of cardiovascular disease. Period.
"The message of this study is that weight gain following smoking cessation does not offset the benefits of smoking cessation on cardiovascular diseases," Clair said. "Doctors should advise all their patients to quit smoking."