Is Your Diet Soda Getting You Drunk?
PHOTO: Mike Floyd/Collect/Rex USA

Cutting calories with diet soda may seem like a good idea -- as long as it's not at a bar.

A new study released in the journal Alcoholism suggests that cutting alcoholic drinks with diet soda makes them more potent than using their full-calorie counterparts. Specifically, researchers found that mixing alcohol with diet (sugar-free) soft drinks resulted in a higher breath alcohol content than mixing alcohol with a regular (sugar-sweetened) soft drink.

"The results were surprising," said Cecile A. Marczinski, assistant professor in the department of psychological science at Northern Kentucky University, and one of the lead investigators of the study.

Researchers served one of three beverages: vodka added to a diet drink, vodka added to a regular drink or a regular soft drink with a vodka scent added so that participants would believe it was an alcoholic beverage. They then sat back while the subjects enjoyed their cocktails.

Those participants drinking the vodka-diet drink cocktails had a significantly higher breath alcohol content and had the highest degree of behavioral impairment among the groups, the study found.

"We are talking about significant differences here," Marczinski said. "Participants who drank diet soda with vodka had blood alcohol contents as high as 18 percent more than when sugar-containing mixers were used."

The theory behind this is that sugar-containing drinks stimulate the stomach much like a meal does. Having some food in your stomach delays stomach emptying, thus delaying absorption of alcohol into the bloodstream. The result is that drinkers get a less-potent hit of alcohol in their systems after drinking.

"This is why southern European countries have lower rates of alcoholism despite their increased alcohol intake," said Petros Levounis, director of the Addiction Institute of New York, who was not involved in the study. "They always drink while eating."

Diet beverages, since they contain no sugar, do not trigger the stomach to delay emptying, allowing alcohol to reach the bloodstream more quickly.

"The choice of what you mix your alcohol with can make a difference," Marczinski said, adding that there may even be potentially harmful consequences for those who regularly request a diet soda with their spirits.

"In the long run, it's more harmful for your body to be exposed to a higher alcohol concentration than a few extra calories," she said.

But not all alcohol experts agree that going diet with your cocktails is all that different. Boris Tabakoff, a professor of pharmacology at the University of Colorado School of Medicine, pointed to the fact that study subjects drank the equivalent of three to four drinks over a five-minute period.

"Few if any bars will serve you a drink that strong," he said. "If you want to chug your alcohol to the point of consuming the equivalent of three to four drinks in five minutes, you should not worry about calories."

Tabakoff further pointed out that calorie-conscious drinkers might do better simply to limit their alcohol intake, noting that alcohol, too, is packed with calories.

More ABC News