Can acesulfame-K in diet drinks and sugar-free snacks cause fatty liver?

What's actually in it

Acesulfame potassium (Ace-K) is an artificial sweetener found in diet sodas, flavored waters, sugar-free gum, protein powders, and low-calorie baked goods. It's often paired with other sweeteners like sucralose or aspartame to improve taste. On labels, it appears as "acesulfame potassium" or "acesulfame K." It's about 200 times sweeter than sugar and passes through your body without being digested, which is why it has zero calories.

What the research says

A 2026 study in Int J Mol Med found that Ace-K triggers non-alcoholic fatty liver disease (NAFLD) by disrupting how liver cells handle fat. The sweetener interfered with a key protein called PPARα, which normally tells the liver to burn fat for energy. When Ace-K blocked this signal, fat accumulated inside liver cells instead of being processed.

The researchers mapped out the chain reaction: Ace-K threw off PPARα signaling, which activated a secondary pathway through a protein called PLCβ, leading to fat storage and liver inflammation. The damage looked like the early stages of fatty liver disease.

Fatty liver is now the most common liver condition in the world, and it can progress to scarring, liver failure, and liver cancer if left unchecked. Many people switch to diet drinks to avoid sugar, not realizing the replacement might harm their liver through a completely different pathway.

Water, sparkling water, or drinks sweetened with stevia or monk fruit avoid this problem. If you drink multiple diet beverages a day, even cutting back gradually can lower your Ace-K load.