People get concerned that the artificial sweeteners may spike insulin. There is some (sketchy iirc) evidence to suggest it does whilst other studies dispute this. If fasting for weight loss then diet (read minimal or zero calorie drinks) are ok.
I am not a biologist but I do know a bit of chemistry. If you are fasting then I would believe it is totally fine form a weight loss perspective. It may spike your insulin but since you won’t have any calories to metabolize that won’t matter. It may make you feel terrible and I have no idea how it will impact your gut flora but it won’t magically create more weight on you. I would guess that it will make you feel tired and weak as your inulin levels increase but since you aren’t diabetic it shouldn’t be too bad. I would also suggest you don’t do it too much as it may affect your pancreas.
Aspartame is just a super sweet type of sugar. It isn’t zero cal, it is just 1/200th the amount of calories for the same sweetness as glucose.
It’s very acidic (like, stripping copper pennies levels). Aside from the artificial sweeteners, I’d be worried about pumping cup fulls of a corrosive liquid on an empty stomach.
Tea + salts is a much safer idea! And you can still get that caffeine boost, along with appetite suppression.
Some people do. I have heard that it can cause people to be hungrier, and not do so well fasting. I know for me it’s that way…so I just stick with water myself.
It is your choice…can try it and see if you like.