Diet Soda Shouldn't Mix With Alcohol

Everyone knows that drinking alcohol means drinking calories. That’s inevitable, but many people decide that the calories are worth it. Some people choose to minimize the calorie impact of their favorite mixed drink by substituting diet soda for the typical, sugar-sweetened soda. New research suggests that this can have unexpected results.

Dr. Cecile Marczinski is a professor at Northern Kentucky University. She has researched a wide range of alcohol-related subjects, with a special focus on the drinking habits (and related impacts) of college students. Her latest research investigated the impact of diet sodas when mixed with alcohol.

Many mixed drinks include carbonated beverages as a mixer. The soda softens the sharp taste of the alcohol and the carbonation adds a lightness to the mouth feel. The choice of mixer was studied in Dr. Marczinski’s research, which is published in the journal Alcoholism: Clinical & Experimental Research.

Research volunteers drank alcoholic mixed drinks under controlled circumstances. During one visit, their drinks used sugar-sweetened sodas as mixers. At the end of the drinking session, their blood alcohol level was measured, along with their personal feelings about their level of impairment.

The volunteers returned a week later for the same experience, but this time the drinks used sugar-free sodas as mixers. Again, at the end of the session their blood alcohol level and feelings about their level of impairment were recorded.

The differences between the two drinking sessions were surprising. The session using sugar-free mixers resulted in blood alcohol levels that were an average of 18% higher than when using sugar-sweetened mixers. The actual amount of alcohol consumed during the two sessions was the same, just the resulting level of inebriation was different.

Also surprisingly, the volunteers reported that they felt the same relative level of impairment at each session. That means that the volunteers were not aware of their increased level of drunkenness when drinking sugar-free drinks.

This effect may be caused by the difference between how our body reacts to drinking liquids containing sugar compared to liquids without sugar. The sugar-free alcoholic beverages were processed very quickly, dumping the alcohol into the bloodstream soon after drinking. The sugar-sweetened beverages were treated as food by the body, so the passage into the small intestine, where the alcohol joins the blood stream, was delayed.

So consider your mixer carefully! You may save a few calories, but it could be at the expense of your blood alcohol levels.