If the idea of drinking a calorie-free beverage that still has a lot of flavor sounds too good to be true, it probably is. We’re talking about diet soda.

While the idea of drinking the diet version of your favorite soda flavor can sound like a great way to cut calories and reduce your sugar intake, the risk might not be worth it. A new study by the American Heart Association and American Stroke Association found a strong link between women who drank 2 or more diet sodas per day and the chances of having a stroke.

There were over 80,000 postmenopausal women who participated in this study. The women who drank 2 or more diet sodas per day had a 31% higher risk of having a clot-based stroke. They also had a 29% higher risk of having heart disease. Their risk of dying from any cause whatsoever increased by 16%.

These results were determined after looking at lifestyle factors. The risk of having a stroke is even greater for people who drink 2 or more diet sodas per day and who are also African American or obese, which means a body mass index over 30.

Yasmin Mossavar-Rahmani, an associate professor of clinical epidemiology and population health at the Albert Einstein College of Medicine in the Bronx, New York, was the lead author of the study. She said, “African-American women without a previous history of heart or diabetes were about four times as likely to have a clot-based stroke,” and “Women who, at the onset of our study, didn’t have any heart disease or diabetes and were obese, were twice as likely to have a clot-based or ischemic stroke.”

While it clearly looks like there is some link between drinking diet soda and having a stroke, it’s still not clear why. Mossavar-Rahmai asks, “What is it about these diet drinks? Is it something about the sweeteners? Are they doing something to our gut health and metabolism? These are questions we need answered.”

While the diet soda industry points out that artificial sweeteners and diet drinks can be an effective way to help people lose weight, The American Heart Association only recommend this strategy for people who “find it difficult to move directly from sugary drinks to water,” according to Rachel Johnson, University of Hawaii nutrition professor and chairwoman of the writing group for that scientific advisory. Johnson recommends limiting diet soda intake due to the potentially serious side effects that studies have shown.

The takeaway is this: Drink diet soda with caution, and if you’re trying to lose weight and are having a hard time switching from regular soda to water, only drink diet soda as a brief stopover on your way to drinking water.

Meanwhile, the bottled water industry is exploding. In 2016, for the first time, more bottled water was sold than carbonated beverages, and it has been that way ever since.

How often do you drink diet soda?