Controlled human intervention trials consistently demonstrate that the consumption of low-calorie sweeteners at typical intake levels has no adverse health effects.

Study: The effects of low-calorie sweeteners on energy intake and body weight: a systematic review and meta-analyses of sustained intervention studies

This study looked at what happens when people use low-calorie sweeteners instead of sugar, and found they didn’t cause any harmful side effects — even after weeks or months of use.

Study: Low-calorie sweeteners in the human diet: scientific evidence, recommendations, challenges and future needs. A symposium report from the FENS 2019 conference

This study says that when people use low-calorie sweeteners like those in diet sodas, there’s no solid proof they’re harmful — and experts agree they’re safe at normal amounts.