BOSTON, March 9 (UPI) -- Women who are normal weight and consume no more than two drinks a day may gain less weight than those who do not drink, U.S. researchers say.

Dr. Lu Wang of Brigham and Women's Hospital in Boston and colleagues studied 19,220 U.S. women age 39 or older who had a body mass index within the normal range 18.5-25.

Participants reported how many alcoholic beverages they typically drank per day: 38.2 percent reported drinking no alcohol, 32.8 percent drank less than 5 grams, 20.1 percent drank 5 to less than 15 grams, 5.9 percent drank 15 to less than 30 grams and 3 percent drank 30 grams per day or more. Alcohol contains about 7 calories per gram -- or approximately 28 grams per ounce.

After an average 13 years of follow-up, women who did not drink alcohol at all gained the most weight, with weight gain decreasing as alcohol intake increased. 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 -- almost 30 percent lower than that of non-drinkers.

The study, published in the Archives of Internal Medicine, said the association between alcohol and weight loss was noted for red wine, white wine, beer and liquor with the strongest association in red wine and a weak yet significant association for white wine, the study authors said.