It’s called a diet drink, so it should be a good choice for those of us trying to lose weight, right? Not so fast, say researchers at the University of Nottingham. In their study, which was published this month in the medical journal Diabetes, Obesity and Metabolism, they compared the impact of drinking either water or a diet drink on weight loss efforts. All participants in the study were overweight or obese women with diabetes, and regular consumers of diet drinks prior to their participation. Over the course of 24 weeks, they were all placed on the same weight control diet. Half of them were asked to replace the diet beverage with water for five days of the week after lunch. The other half continued consuming the diet beverage after lunch.

Their results may surprise you. We assume diet drinks to be a safe bet, since they aren’t contributing any extra calories to our diet. In fact, the researchers found that the group that consumed water lost significantly more weight than the diet drinkers. After 24 weeks, the water drinkers had lost an average of 14 pounds, while the diet drinkers lost just 11.5 pounds. That could add up to about 5 extra pounds of weight loss a year, if we choose water over a diet drink just a few days a week!

The exact reasons for the increased weight loss in water drinkers is not clear at this time, but it is always a healthy bet to consume water as your primary beverage. At minimum, we should aim to drink 64 oz, or about 8 cups, of water daily. To make sure that you are getting enough, check out the Food Diary feature on the platform to help you keep track!