Lars Klove for The New York Times

Dieters are often advised to stop drinking alcohol to avoid the extra calories lurking in a glass of wine or a favorite cocktail. But new research suggests that women who regularly consume moderate amounts of alcohol are less likely to gain weight than nondrinkers and are at lower risk for obesity.

The findings, reported this week in the Archives of Internal Medicine, are based on a study of 19,220 United States women aged 39 or older who, at the start of the study, fell into the “normal weight” category based on their body mass index. Researchers at Brigham and Women’s Hospital in Boston tracked the women’s drinking habits over 13 years. About 60 percent of the women were light or regular drinkers, while about 40 percent reported drinking no alcohol.

Over the course of the study, 41 percent of the women became overweight or obese. Although alcohol is packed with calories (about 150 in a six-ounce glass of wine), the nondrinkers in the study actually gained more weight over time: nine pounds, on average, compared with an average gain of about three pounds among regular moderate drinkers. The risk of becoming overweight was almost 30 percent lower for women who consumed one or two alcohol beverages a day, compared with nondrinkers.

The findings are certain to be confusing for women who continue to receive conflicting messages about the health benefits and risks of alcohol. Although moderate drinking is associated with better heart health, regular drinking also increases breast cancer risk.

The trend toward less weight gain among drinkers doesn’t appear to hold true for men. A 2003 study of British men showed that regular drinkers gained more weight than nondrinkers. Studies suggest that drinking alcohol has different effects on eating habits among men and women. Men typically add alcohol to their daily caloric intake, whereas women are more likely to substitute alcohol for food. In the Archives study, women who drank alcohol reported fewer calories from food sources, particularly carbohydrates.

In addition, there may be differences in how men and women metabolize alcohol. Metabolic studies show that after men drink alcohol, they experience little if any metabolic change. But alcohol appears to slightly speed up a woman’s metabolism.

The link between consumption of red wine and less weight gain was particularly pronounced in the Archives study. Some studies have suggested that resveratrol, a compound present in grapes and red wine, appears to inhibit the development of fat cells and to have other antiobesity properties.

The findings don’t mean women should rush to drink alcohol to lose weight. Other research shows that once a person is already overweight, her alcohol metabolism is more efficient, and so an overweight woman may gain more weight from alcohol than a lean woman. The data do, however, suggest that for many women facing weight problems, the extra calories are probably not coming from alcoholic beverages.