For anyone trying to lose weight, one of the first indulgences to get cut from their diet is alcohol. After all, alcohol packs 7 kcal/g a good-size glass of wine contains more than 150 calories an extravagance that could stymie efforts to slim down.
But maybe it's time to put that wineglass back on the table. New findings from researchers at Brigham and Women's Hospital in Boston reveal that women who drink moderately are less likely to gain weight over time than those who don't. Before you start stocking your kitchen with vodka instead of vegetables, however, experts caution that the relationship between alcohol and weight may not be that simple.
Led by Dr. Lu Wang, preventive-health experts at Brigham conducted the first long-term study of women's drinking habits and weight gain. The study involved 19,220 women over the age of 38 who were of normal weight. Researchers asked the women about their alcohol consumption over the past year and recorded how much of four different types of alcoholic beverages they consumed beer, red wine, white wine and liquor. The researchers measured the average ethanol content of each beverage and then calculated each volunteer's average alcohol intake; they also weighed each woman five times over the course of the follow-up period.
After 13 years, women consuming the highest amount of alcohol per day (more than two drinks daily) were 30% less likely to be overweight and nearly 70% less likely to be obese than nondrinkers, the team found. "We certainly don't want to encourage nondrinkers to adopt alcohol as a method for weight control, but we were surprised by the strength of the association," says Dr. JoAnn Manson, chief of preventive medicine at Brigham and Women's and a co-author of the study, published in the Archives of Internal Medicine.
The scientists controlled for a suite of obvious factors that could have separately contributed to the women's weight, such as age, smoking, physical activity and other lifestyle and behavioral habits. But even after accounting for these potential confounders, the link remained between higher alcohol consumption and a lower risk of being overweight or obese.
The association led the team to consider several possible explanations. First, it could be that women who drink more simply substitute alcohol for other sources of calories in essence adopting a form of the liquid diet. Indeed, when the researchers analyzed the data, it appeared that the women who drank the most got fewer of their total calories from nonalcoholic sources than other women, but also consumed the most calories overall. Women having one to two drinks daily, for example, consumed 1,738 kcal/day, compared to the 1,670 kcal/day of teetotalers, but they took in 177 fewer kcal/day from nonalcoholic sources. Whether or not this substitution is a conscious decision on the women's part still isn't clear and the study wasn't designed to find out.
Second, there is evidence that alcohol may cause physiologic changes to appetite and metabolism that may drive women to lose weight as they drink more. Women may metabolize alcohol differently from men, using a more inefficient, high-energy process that causes them to burn more of the calories from alcohol than men, which in turn leads to a net loss in caloric intake. But more research is needed to determine exactly how women process alcohol and the different ways in which the liquid calories are absorbed by the body. "It's very likely there is a combination of physiologic, metabolic and some behavioral changes," says Manson regarding the association between drinking and weight.
It's worth noting that while replacing some foods with alcohol may seem like an enticing weight-loss loophole, it isn't necessarily good for health. "Displacing 200 calories or so from food with alcohol probably has a detrimental effect on diet quality and on overall health," notes Dr. David Katz, director and co-founder of the Yale University Prevention Research Center. "If you look meticulously at nutrient intake, there might be important deficiencies there."
That underscores the complex effect that alcohol has on the body, especially in women: excess alcohol can lead to a greater risk of developing breast cancer, while moderate consumption of a glass of wine a day may help reduce heart disease risk. So whatever potential gains a nightly beer or glass of red may have on slimming down love handles, the benefits must be balanced against the other potential gains and risks of alcohol consumption.
Putting these results in the context of previous work showing the heart benefits of moderate drinking, Katz prefers to look at it this way: "This study suggests that you can probably make room for moderate alcohol consumption and not have it result in weight gain. But we certainly don't want to suggest to people to go out and drink more alcohol as a weight-control strategy."