Sure, Diet Coke doesn’t have any calories, but a new study found drinking sugar-free soda leaves your body wanting something sweet. And researchers have an explanation why: Diet drinks play a terrible trick on your mind. (The study was conducted on fruit flies and mice, but researchers say the findings likely apply to humans.) Our brains are wired to expect a rush of calories after tasting something sweet, but artificial sweeteners don't deliver, which leaves us craving sugary foods. So next time you grab a diet drink, know your body expects a treat will follow.