from "Alcohol + diet drinks may increase intoxication" on ScienceBlog:
While it is known that food delays the stomach emptying, thus reducing BrAC [breath alcohol concentration], only recently has the role of nonalcoholic drink mixers used with alcohol been explored as a factor influencing BrAC. A new comparison of BrACs of alcohol consumed with an artificial sweetener versus alcohol consumed with a sugared beverage has found that mixing alcohol with a diet soft drink can result in a higher BrAC.
***"In natural drinking settings, such as bars and nightclubs, young women are significantly more likely than young men to order drinks mixed with diet cola," said [Dennis L] Thombs [professor and chair of the department of behavioral and community health at UNT Health Science Center]. "I suspect this occurs because young women tend to be more weight conscious than young men. Thus, from a public health perspective, artificially sweetened alcohol mixers may place young women at greater risk for a range of problems associated with acute alcohol intoxication."