The truth about alcohol and weight gain

But there’s a difference between hearing your friend’s cousin lost a bunch of weight after she stopped drinking beer and knowing the actual science around weight and alcohol.

According to a new study published in the American Journal of Preventative Medicine, people who drink heavily when they’re younger have a higher risk of gaining excess weight and becoming overweight or obese when they’re older.

For the study, researchers analyzed data from the U.S. National Longitudinal Study of Adolescent to Adult Health from people when they were in their late teens and early twenties and again when they were in their mid- to late-twenties and early thirties.

People who were heavy drinkers (which is defined by the Dietary Guidelines for Americans as having four or more drinks on any day or eight or more drinks per week for women) had a 41 percent higher risk of going from a normal weight BMI to an overweight BMI when compared with people who weren’t heavy drinkers, and a 36 percent higher risk of going from an overweight BMI to an obese BMI by the time they hit their mid-twenties. If someone was already obese, they had a 35 percent higher risk of staying that way and gaining more weight.

As a result of their findings, the researchers concluded that heavy drinking should be part of the discussion when it comes to talking about healthy eating and weight loss.

“It’s important to look at alcohol in terms of calories,” says Fatima Cody Stanford, M.D., instructor of medicine and pediatrics at Harvard Medical School and obesity medicine physician at Massachusetts General Hospital. And alcohol definitely has calories: According to the Dietary Guidelines for Americans, 12 ounces of regular beer can have about 150 calories, five ounces of wine might have about 120 calories, and a seven-ounce rum and Coke has about 155 calories. And, if you’re drinking a lot of those in a week, it can add up. “I try to get patients to deviate as much as they can or consume it sparingly,” Stanford says.

People also tend to underestimate how much they’re drinking, Stanford says. A serving of wine, for example, is five ounces, but you probably pour more than that when you’re having a glass at home. “Whatever you think you’re having, you probably need to cut that in half,” Stanford says.

It’s not just about the calories from alcohol itself: Drinking can lower your inhibitions and sense of awareness, making you much more likely to mindlessly eat when you have a buzz, says Alissa Rumsey, R.D., owner of Alissa Rumsey Nutrition and Wellness. “While you may be able to realize you are full and stop after one slice of pizza when you are sober, it's harder to read those fullness signals when you've had a few drinks,” she says. “People often end up eating when they aren't necessarily hungry.”

Excess alcohol can also turn to fat in your liver and can raise the amount of fat in your blood, says Sonya Angelone, R.D., a spokeswoman for the Academy of Nutrition and Dietetics. It’s also more likely to be stored in your body as fat, she says.

Add all of this together and it’s easy to see how drinking heavily can cause you to gain weight over time. That doesn’t mean you have to totally swear off alcohol if you want to lose weight—you just need to be smart about drinking. “The extra calories from moderate drinking (one serving of alcohol for women a day or two servings for men per day) can certainly fit into the calorie allotment for weight maintenance,” Angelone says. The important thing is that you factor those calories in along with what you eat, she says.

Rumsey agrees. “If you enjoy a moderate amount of alcohol and it is something that is important to you, I don't recommend restricting yourself to try to lose weight,” she says. “This type of restriction tends to backfire.” If you want to make lower-calorie drink choices, she recommends opting for wine or beer, or having cocktails made with low-sugar add-ins like soda water and a splash of fruit juice.

Again, you can drink and still lose weight—just keep it within moderate levels and you should be fine.