March 8, 2010 -- It might be time to add weight control to the growing list of potential benefits for light to moderate drinking.
Those who drank the equivalent of one to two drinks a day -- be it beer, wine, or liquor -- were 30% less likely than non-drinkers to become overweight or obese.
The study was conducted by researchers at Boston's Brigham and Women's Hospital; it's published in the Archives of Internal Medicine.
Study co-researcher Howard S. Sesso, ScD, MPH, cautions that people who do not drink alcohol should not take up the habit to keep from gaining weight.
"That would not be a good idea," he says. "But for women who already drink in moderation, this can be seen as encouraging. Alcohol has traditionally been thought of as empty calories, but in this study light to moderate drinking was associated with less weight gain, not more."
Drinkers vs. Teetotalers
The study included more than 19,000 women aged 39 and older enrolled in the Women's Health Initiative.
None of the women were overweight when they entered the study, and all were asked about their daily alcohol consumption in an initial questionnaire.
About 40% reported that they did not drink at all, while 33% reported drinking the equivalent of about two alcoholic beverages a week. Another 20% reported having about a drink a day, 6% drank one to two alcoholic beverages a day, and 3% reported drinking more than this.
Over an average of 13 years of follow-up, most of the women in the study gained some weight.
But the women who reported being teetotalers when they entered the study gained the most weight. The women who reported drinking some alcohol, but no more than two drinks a day, gained the least.
This was true even after the researchers factored in variables that influence weight gain, including age, race, total calorie intake, activity level, and smoking status.
A typical non-light beer, 8-ounce glass of wine, or single-shot cocktail contains about 15 grams of alcohol.
Women in the study who drank from 15 to less than 30 grams of alcohol a day were 30% less likely to become overweight or obese than non-drinkers; the risk was 24% lower for women who drank from 5 to less than 15 grams of alcohol a day.
Past Research on Alcohol and Weight Gain
The study is not the first to suggest that drinking alcohol in moderation can benefit the waistline.
Epidemiologist Ahmed A. Arif, PhD, and Texas Tech University colleagues found the same thing when they analyzed data from a large national health survey in 2005.
Men and women in the survey who drank alcohol in moderation were less likely than non-drinkers to be obese.
But binge drinking and drinking four or more drinks a day were associated with an increased risk for being overweight or obese.
Arif, who is now an associate professor of epidemiology at the University of North Carolina, Charlotte, says more research is needed to determine if moderate drinking really helps protect against weight gain or if other lifestyle factors explain the association seen in his study and the latest one.
"We can't say what the underlying biological mechanisms might be if alcohol is protective," he tells WebMD. "And until we understand this better we can't say that drinking alcohol is protective against obesity."