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Post-smoking weight gain doesn't harm heart

By Catherine Winters


Plenty of smokers swear they’ll quit. But nagging concerns about post-smoking weight gain, and perhaps the effect it'll have on their risk for cardiovascular disease, may prompt some to put their plans to quit on the back burner. Now, a new study suggests that post-smoking weight gain won't raise people's risk for cardiovascular disease or death even if they have diabetes. 

Researchers found that people without diabetes who stopped smoking reduced their risk for heart attack, stroke or cardiovascular death by about 50 percent. Gaining weight didn’t change that reduction in risk. People with diabetes — a group that has to be especially careful about weight gain — had the same reduction in risk regardless of how much weight they gained.

During the study, researchers analyzed data on 3,251 people enrolled in the Offspring Cohort of the landmark Framingham Heart Study. That study was desgined to identify the causes of heart disease. People in the Offspring Cohort, which began in 1971, underwent regular physical examinations. During these visits, study participants were weighed; their body mass index, or BMI, was calculated; their cholesterol and blood glucose levels were measured; and their smoking habits were recorded.

The researchers found that on average, smokers, nonsmokers and long-term quitters —those who had been smoke-free for four or more years — gained an average of one to two pounds between study visits, which occurred every four years. Recent quitters — those who had quit within the previous four years — gained much more weight, about five to 10 pounds. At their first examination, 31 percent of people in the study smoked. By the fourth examination, about 20 years later, just 13 percent did.

Among people without diabetes, recent quitters gained much more weight —nearly six pounds — than long-term quitters and smokers, who each gained about a pound, and nonsmokers who gained about three pounds. Among people with diabetes, recent quitters gained nearly eight pounds on average; smokers, nearly two pounds; long-term quitters, zero; and nonsmokers one pound.

Typically, people who quit smoking gain between about seven and 13 pounds within the first six months, a gain that lingers over time. Death from cardiovascular disease increases by 40 percent for each five-unit increase in body mass index, or BMI. In a person who is 5 feet 7 inches tall and weighs 180 pounds, that's the equivalent of a 30-pound gain, according to the researchers.

During about 25 years of follow-up, the researchers found that 631 cardiovascular events had occurred. Of these, 337 (53.4 percent) were heart attacks and 147 (23.3 percent) were strokes.

Among people without diabetes, recent quitters were 37 percent less likely to have a heart attack; long-term quitters were 68 percent less likely; and nonsmokers were 81 percent less likely. Among people with diabetes, recent and long-term quitters were 60 percent less likely than smokers to suffer a heart attack; and nonsmokers were 85 percent less likely.

"We knew people gained weight after they stopped smoking," said senior study author researcher Dr. James B. Meigs of the general medicine unit at Massachusetts General Hospital and an associate professor of medicine at Harvard Medical School. "We didn't know if that would impact the size of the benefit of stopping smoking."

The findings suggest that the benefits of quitting trump weight gain. "From a public health perspective, people who stop smoking will gain a little weight, but it doesn't mitigate the benefits," added Meigs. "This study allows doctor to say to patients, 'If you stop smoking, within a few years, you'll have the same chance of dying from a heart attack as you would if you hadn’t smoked.' Stopping smoking is really beneficial and again, we can say this with certitude."

Of the major risk factors for cardiovascular disease — namely diabetes, smoking, high blood pressure, high cholesterol and age — weight gain usually influences only three of those,  Meigs said. "In people who gain weight, their blood pressure tends to go up and their cholesterol and blood sugar levels tend to get a little worse."

As it turns out, "in our study, the weight gain wasn't so big that people were going from Twiggy to Jumbo," Meigs said. "They were gaining a few pounds in the middle distribution of weight from kind of heavy to a little heavier." 

Indeed, the most overwhelming risk factor for having a heart attack or stroke is cigarette smoking. "A little weight gain that raises blood pressure, blood glucose or cholesterol isn’t nearly harmful enough to overcome the benefits of not smoking," Meigs said.

The study is published today (March 12) in the Journal of the American Medical Association.