Alcohol has been labeled "empty calories" in recent years, a potential factor behind weight gain. But a new Spanish study has found that people who drink wine in moderation are actually gaining less weight than the general population. What they haven't been able to determine is why.
Obesity is a known risk factor for a host of chronic diseases, and scientists are keen to discover potential ways to control this growing health epidemic. In the past four decades, alcohol consumption in some Western cultures has doubled. A team of medical researchers at the University of Navarra conducted a meta-analysis of leading studies on alcohol and weight and published their findings in the August issue of the medical journal Nutrition Reviews.
In the text, they argue that growing alcohol consumption, and the potential impact on weight, needs more consideration in determining public health policy. "Nearly two-thirds of U.S. adults are either overweight or obese. Following this trend, about three-fourths of the U.S. population could be overweight or obese by 2015," the authors state.
What science does not yet know is whether alcohol is directly contributing to obesity. It's highly probable, the Spanish researchers say. One gram of alcohol equals 7.1 kilocalories. That puts it right below fat, but above protein and carbohydrates, in terms of caloric density. And today people tend to drink alcohol in addition to their food intake, not as a substitute for other forms of nutrition. Supplementing diets with beer, wine or spirits may cause daily energy intake to continuously exceed daily energy expenditure, leading to weight gain.
In their analysis, the team found evidence that alcohol is contributing to obesity in heavy spirits or beer consumers. But light-to-moderate wine drinkers, those who consumed one or two glasses a day, gained less weight than the general population. That was not the case for those who drink three glasses or more. The reasons behind the findings are unclear.
"This might be explained by a healthier overall dietary pattern of wine drinkers," the researchers write. Some scientists have suggested that red wine induces certain enzymes to improve the metabolism of fat cells. Others suggest that the red-wine compound resveratrol inhibits the conversion of sugars into fat. The Spanish scientists say the high levels of antioxidants in red wine may reduce the high levels of inflammation associated with obesity.
The same team, working with the department of endocrinology at the University's hospital, conducted their own study on 9,318 patients and found that moderate wine drinkers showed the least amount of yearly weight gain, compared to beer and spirits drinkers. The results were published in the July-August issue of Nutrition.
Despite the positive results for responsible wine drinkers, the scientists do not recommend broad changes to public health policy based on the findings. "If you drink alcohol it is better to drink wine," lead author Carmen Sayon-Orea told Wine Spectator, "but not by any circumstances would we advise people to start drinking wine to stay lighter."