Smokers who want to kick the habit should not let the fear of gaining weight stop them. Researchers have found that most ex-smokers gain weight quickly, but after two years they tend to lose about half of what they gained.
"They probably won't lose it all," said Dr. Yue Chen of the Royal University Hospital at the University of Saskatchewan in Saskatoon. "But most everyone gains weight as they age. After two or three years, the weight gain is quite close to that of non-smokers."
People gain an average of four pounds as they age, said Dr. Chen, who reported his findings last week at the American Lung Association meeting in Miami.
Dr. Chen and his colleagues surveyed 1,202 residents of Humboldt, Saskatchewan, in 1977 and reinterviewed 709 of them in 1983. About 140 people in the follow-up group had quit smoking.
Weight gain was highest in people who had recently stopped smoking, Dr. Chen found. Women in that group gained an average of about 11 pounds, and men gained an average of eight pounds.
But in people who had quit smoking for between two and six years, the weight gain was close to the four-pound average for all people, Dr.
Smokers may gain weight after they quit because they eat more as compensation. Nicotine also is thought to speed metabolism, causing the body to burn more calories. So smokers who quit tend to burn calories more slowly, thus gaining weight, until their metabolic rate stabilizes, said Richard Keesey, a professor of psychology and nutrition at the University of Wisconsin School of Medicine in Madison.
"It's not a large gain, and then things normalize again," the professor said. "They go back pretty close to what their weight was before."
Researchers at the Centers for Disease Control, in a study last year, found that a small percentage of ex-smokers gain a lot of weight.
In that study, 10 percent of men and 13 percent of women gained 29 pounds or more within five-and-a-half years of quitting.
The average weight gain for ex-smokers was six pounds for men and eight pounds for women.