
“A study to be
published in a forthcoming issue of Alcoholism: Clinical and Experimental Research, found that using diet soda as a mixer can
dramatically increase breath-alcohol content (BAC) without increasing your
awareness of being impaired.”
Research into the impact of mixers on breath alcohol
concentration (BrAC) showed that those who drink white rum mixed with
diet cola had higher BrAC than those who drink the same amount of rum mixed
with regular cola.
Test subjects that consumed alcohol
with low-calorie mixers had nearly a fifth more alcohol on their breath than
their high-calorie counterparts, an article published in Drug and
Alcohol Dependence said.
It referred to a previous study showing that as much as an 18%
higher BrAC level was detected with carbonated diet soda compared to
calorific soda. The study suggests that
alcohol is more readily absorbed into the blood stream with low-calorie mixers
than with high-calorie mixers.
Consumers often try to limit the calorie intake of their
alcoholic drinks by using diet mixers. Those concerned
about the speed with which they become intoxicated could rethink their choice
of mixer based on the findings.

You can read more on the subject at http://healthland.time.com/2013/02/06/diet-soda-mixers-can-lead-to-quicker-intoxication/