Using sugar-free sweeteners doesn’t make you eat more fat or protein than if you used regular sugar or just drank water—so their main job is just to cut down carbs and calories.

Drinking diet soda instead of water doesn’t make you eat fewer calories — it only helps cut calories if you’re swapping it for sugary drinks instead.

If you swap sugar for artificial sweeteners, you’ll eat less sugar—by a lot—but if you drink water instead, you get the same low sugar intake, so the sweeteners don’t help any more than water does.

Using sugar substitutes like stevia or aspartame doesn’t make you more likely to have bad health effects than eating sugar, drinking water, or taking a fake pill—so they’re probably safe if you’re trying to lose weight.

If you swap out sugary drinks and snacks for ones with artificial sweeteners, you might eat about 175 fewer calories a day, which could help you manage your weight.

If you swap sugary foods and drinks for ones with artificial sweeteners, you might lose about 1 kg and eat fewer calories—especially if you cut out a lot of sugar. But this only works if you’re replacing sugar, not just adding sweeteners on top.