Drinking alcohol mixed with diet soda may get you drunk faster than drinking alcohol mixed with regular soda.

The simple choice of whether or not to mix liquor with a diet or regular soda may affect how intoxicated you get, a new study suggests.

In the study, men and women ages 21 to 33 who drank vodka mixed with diet soda had breath alcohol concentrations that were 18 percent higher after 40 minutes compared with people who drank the same dose of vodka mixed with regular soda.

In fact, after three to four drinks, people who used diet soda as a mixer had a breath alcohol level that exceeded the legal limit for an adult operating a motor vehicle. People who used regular soda in their drink did not.

What’s more, people who used diet mixers scored more poorly on a test of reaction time that people who used regular mixers, although both groups reported feeling similar levels of intoxication.

The study was small — just eight men and eight women participated — so more research is needed to confirm the findings. And although results from breath alcohol tests are usually consistent with those from tests of blood alcohol, there can sometimes be a discrepancy between the two methods, so the study should be replicated using blood alcohol tests, the researchers said.

But the findings suggest that diet mixers, although lower in calories, may have insidious effects, said study researcher Cecile Marczinski, an assistant professor of psychology at Northern Kentucky University.
People “think they’re saving some calories by drinking their alcohol with a diet drink, [but] it’s much more harmful to the body to have a high blood alcohol concentration,” Marczinski said.