9 Mar 2010 --- Normal-weight women who drink a light to moderate amount of alcohol appear to gain less weight and have a lower risk of becoming overweight and obese than non-drinkers, according to a report in the March 8 issue of Archives of Internal Medicine, one of the JAMA/Archives journals.

More than half of American adults drink alcoholic beverages, according to background information in the article. Alcohol contains about 7 calories per gram (with approximately 28 grams per ounce) and alcohol drinking may possibly lead to weight gain through an imbalance of energy consumed and energy burned. However, research has not consistently provided evidence that consuming alcohol is a risk factor for obesity.

Lu Wang, M.D., Ph.D., of Brigham and Women's Hospital, Boston, and colleagues studied 19,220 U.S. women age 39 or older who had a body mass index (BMI) in the range classified as normal (18.5 to 25). On an initial questionnaire, participants reported how many alcoholic beverages they typically drank per day. A total of 7,346 (38.2 percent) reported drinking no alcohol; 6,312 (32.8 percent) drank less than 5 grams; 3,865 (20.1 percent) drank 5 to less than 15 grams; 1,129 (5.9 percent) drank 15 to less than 30 grams; and 568 (3 percent) drank 30 grams per day or more.

Over an average of 13 years of follow-up, women on average gained weight progressively. Women who did not drink alcohol at all gained the most weight, with weight gain decreasing as alcohol intake increased. A total of 7,942 (41.3 percent) women who initially had normal weight become overweight or obese (BMI of 25 or higher), including 732 (3.8 percent) who become obese (BMI of 30 or higher). Compared with women who did not drink at all, those who consumed some but less than 40 grams per day of alcohol were less likely to become overweight or obese. Women who drank 15 to less than 30 grams per day had the lowest risk, which was almost 30 percent lower than that of non-drinkers.

"An inverse association between alcohol intake and risk of becoming overweight or obese was noted for all four types of alcoholic beverages [red wine, white wine, beer and liquor], with the strongest association found for red wine and a weak yet significant association for white wine after multivariate adjustment," the authors write.

The authors caution that, given potential medical and psychosocial problems related to drinking alcohol, its beneficial and adverse effects for each individual must be considered before making any recommendation about its use. "Further investigations are warranted to elucidate the role of alcohol intake and alcohol metabolism in energy balance and to identify behavioral, physiological and genetic factors that may modify the alcohol effects," they conclude.