Switching to diet soda may seem like a good idea if you’re trying to lose weight but, actually, it appears the opposite is true — diet drinks encourage weight gain. A new study suggests that the artificial sweeteners in diet soda could be sabotaging your weight loss efforts.

Over 40 percent of U.S. adults use non-nutritive (artificial) sweeteners to satisfy their sweet tooth and help them lose or maintain their weight, but the health consequences of these calorie-free sweeteners are controversial. Sure, they make it easier to skip sugary calories, but some studies show artificial sweeteners to be helpful, while others suggest they contribute to weight gain, type 2 diabetes and perhaps other metabolic disorders.

After drinking the beverages that contained sucralose, some people in the study showed increased activity in parts of the brain that control food cravings and appetite compared to the effect of beverages containing table sugar.

Artificial sweeteners have also been suspected of causing depression, headaches, an increased risk of cancer, increased appetite and damage to the gut microbiome.

To get a clearer picture of the effects of nonnutritive sweeteners, researchers at the University of Southern California’s Keck School of Medicine followed 74 people — 37 men and 37 women for three visits. Each person was identified as being at a healthy weight, overweight or obese. At all three visits, people in the study drank either about three ounces of a beverage sweetened with table sugar, sweetened with the artificial sweetener sucralose or water.

During the next two hours, researchers used MRIs to study how regions of the brain involved in appetite and food cravings reacted when the study participants were shown pictures of foods like burgers and donuts. Blood sugar, insulin and other metabolic hormone levels were checked, and the amount of food the participants ate at a snack buffet was observed.

After drinking the beverages that contained sucralose, there was increased activity in parts of the brain that control food cravings and appetite in women and in obese individuals when compared to beverages containing table sugar. The levels of hormones that signal the body it feels full decreased as well, suggesting that artificial sweeteners may not suppress hunger.

Finally, at the snack buffet, women who drank beverages containing sucralose ate more than men did.

“By studying different groups we were able to show that females and people with obesity may be more sensitive to artificial sweeteners,” researcher, Kathleen Page, explained in a statement. “For these groups, drinking artificially sweetened drinks may trick the brain into feeling hungry, which may in turn result in more calories being consumed.”

Diet sodas may not be worth making part of your weight loss diet. Given the controversy surrounding them, it might be better to avoid them altogether, especially if you’re not losing weight.

Plain water is calorie-free and can be dressed up to be more appealing by adding slices of citrus fruits or cucumbers, berries, melon balls or herbs such as mint or basil. If you want some fizz, use sparkling water. There’s nothing controversial about that.

The study is published in JAMA Network Open.