So you thought switching to diet soda would be healthier for you? Maybe not, says a new study. Researchers from the University of Minnesota found a link between artificially sweetened cola and metabolic syndromes—the collection of risk factors for heart disease that include obesity, high cholesterol and blood sugar levels. Data showed that people who drank one diet drink a day had a 34 percent greater chance of developing metabolic syndromes than those who did not.

The causes aren’t clear. They could stem from chemical content or to the eating habits of people who consume these syrupy dark drinks. Your best bet: Quench your thirst with eight glasses of water per day.