MONDAY, Aug. 22 (HealthDay News) -- Tying or untying the knot seems to affect men's and women's waistlines differently: A new study shows that women are more apt to pile on excess pounds after marriage, while men add the weight after a divorce.

"Clearly, the effect of marital transitions on weight changes differs by gender," lead author Dmitry Tumin, a doctoral student in sociology at Ohio State University, said in a university news release.

His team looked at weight gain in the two years following a marriage or divorce among more than 10,000 people in the United States surveyed from 1986 to 2008.

Both men and women who divorced or married were more likely than never-married people to have a small weight gain in the two years following their marital transition, the team found.

In most cases, the weight gain was minor and not a serious health threat. But the risk of incurring a large weight gain was higher among men after a divorce and among women after getting married.

"Divorces for men and, to some extent, marriages for women promote weight gains that may be large enough to pose a health risk," Tumin concluded.

The study didn't examine the reasons why major weight gain is more likely for men after a divorce and for women after marriage, and the research did not go beyond the two-year marital transition period. But the findings fit with previous research.

"Married women often have a larger role around the house than men do, and they may have less time to exercise and stay fit than similar unmarried women," study co-author and sociology professor Zhenchao Qian theorized in the news release. "On the other hand, studies show that married men get a health benefit from marriage, and they lose that benefit once they get divorced, which may lead to their weight gain."

The researchers also found that people over age 30 were most likely to gain weight after marriage or divorce, and the risk grew stronger as people grew older.

This may be because they've settled into certain patterns of diet and physical activity, the researchers said.

"As you get older, having a sudden change in your life like a marriage or a divorce is a bigger shock than it would have been when you were younger, and that can really impact your weight," Tumin said.

The research was to be presented Monday at the annual meeting of the American Sociological Association in Las Vegas.

More information

The U.S. Centers for Disease Control and Prevention outlines how to prevent weight gain.