alt Hacker NewsNot mentioned in the article: there is a really obvious biological effect of aspartame: it triggers your sweetness receptors. And you have them in your mouth (duh!) and elsewhere in your body including in your gut.
https://pmc.ncbi.nlm.nih.gov/articles/PMC6288399/
One might imagine that aspartame triggers the receptors in the gut and that this has some effect. Maybe different sweeteners have different effects, too, since they are metabolized differently.
There's not much question that there's some linkage between perception and chemical processes in the body, but there's also no real evidence that those pathways are causally linked to significant metabolic impact.
Your upper GI system quickly transforms aspartame into constituent substances that are widely present in ordinary food.
Different sweeteners certainly have different impacts, but this thread is about aspartame, the best studied and probably the safest of all of them.