Terms like the “Freshman 15” and “Beer Belly” seem to make it pretty clear: drinking alcohol–especially in excess–leads to weight gain. It certainly makes sense. After all, consuming too much of anything containing calories is likely to lead to you ingesting more calories than you expend, with the inevitable result of no longer fitting comfortably in what used to be your favorite jeans. When you take into account the fact that a gram of alcohol contains 7 calories (compared to 9 calories for a gram of fat and just 4 calories for a gram of protein or carbohydrates), drinking a beer falls somewhere between drinking a regular soda and chugging a glass of drawn butter.
Yes, alcohol contains a lot of calories, but it’s also more complex than that. Because it’s not often something you do while say, playing sports yourself, but rather while you’re watching others play sports on TV, alcohol consumption can actually exacerbate a sedentary lifestyle. And it usually makes you want to eat less healthy foods, which compounds the weight gain problem–especially because the way the body process alcohol interferes with other metabolic processes: because alcohol is toxic, the body works to eliminate it first, and sticks that steak and baked potato away as fat until it can get to it later. The case seems pretty airtight, doesn’t it? Drink too much, weigh too much, end of story.
Well, according to a study by Michael French, Edward Norton, Hai Fang, and Johanna Maclean it isn’t exactly true. The results of their study, which appear in the latest issue of Health Economics, indicate that while an increase in the frequency of alcohol consumption is associated with a statistically significant increase in Body Mass Index (BMI) for men, the effect is so small as to be of no practical significance. An increase in the number of drinks consumed per episode also had a statistically significant positive association with BMI, but again, the effect was practically quite small. In other words, drinking might make you a little heavier, but it doesn’t appear to be the driving factor in major weight gain for a man. However, the study authors suggest that persons who consume alcohol may compensate for this in other ways, like diet and exercise, that would offset the caloric intake from drinking and explain why BMI doesn’t jump with increased alcohol consumption. The authors also find that the small, but significant effects they observed in men do not exist in women. No explanation was provided for this null finding.
Of course, I don’t think that this study should be used to justify drinking to excess. Obviously, the law of conservation of energy dictates that if you don’t change other aspects of your diet or exercise routine, drinking more will cause you to gain weight. And even if you do compensate in other areas to avoid gaining weight, the fact remains that alcohol is harmful to the body when consumed in large quantities for long periods of time. As with most things in life, moderation appears to be the key. But, with the obesity epidemic continually cited as one of America’s worst and growing (pun intended) health problems, studies like this one are useful in identifying contributory factors. If I had the resources to field a large survey, I’d like to do a similar study using self-reported fast food consumption to predict changes in BMI. I’ll bet that would show some pretty large effects. In fact, if we modeled those who routinely ordered at the counter separately from those who use the “drive-thru” we’d be able to control for people who are likely to exhibit compensatory behaviors like exercise and those who are just growing fatter so quickly that you can almost hear them as they do it.