Yes, mixing your rum with diet cola will cut calories. But it may also increase your risk of getting a DUI citation, according to a new study on eight young men. Australian researchers found that cocktails made with diet, versus regular, soda passed through the stomach faster, which meant the alcohol entered the bloodstream more quickly. As a result, the subjects; blood alcohol levels surged .02 points higher on average with the sugar-free mixers—possibly the difference between driving legally and driving drunk. And study author Christopher Rayner, PhD, suspects that women may register an even greater spike. This would be mainly because women typically don;t have as much water in their bodies as men, so the alcohol is less diffused, explains Vijay Ramchandani, PhD, a staff scientist at the National Institute on Alcohol Abuse and Alcoholism. So even if a man and a woman weigh exactly the same, she might show 20 percent higher alcohol levels in the blood than he would. The best way to prevent a diet cocktail buzz is to eat when you drink—obviously something low-cal, or you just blow the advantage of using a diet soda mixer in the first place.