How do low-calorie sweeteners affect your weight? It depends.

In a 2019 study, researchers randomly assigned 123 people with overweight or obesity to drink roughly 40 to 60 oz. a day of Kool-Aid sweetened with sugar, aspartame (Equal), saccharin (Sweet‘N Low), stevia extract (Truvia), or sucralose (Splenda). The sugar-sweetened drink supplied 400 to 560 calories. (Heavier participants got larger servings.)

After 12 weeks, the sugar group had gained 4 pounds and the saccharin group had gained 2½ pounds. The stevia and aspartame groups gained—and the sucralose group lost—about 1½ pounds, but those changes weren’t statistically significant. Glucose tolerance didn’t change in any group.

What to do

Avoid sugary beverages, but don’t assume that all low-calorie sweeteners are equal. Stevia is the safest, because aspartame, sucralose, and (rarely used) saccharin cause cancer in animals. It’s too early to know if sucralose can help people lose weight more than other sweeteners.

Want more information about sweeteners (and other chemicals used in foods)? Check out Chemical Cuisine.