I used to drink diet soda and consume diet everything. I grew up with packets in the house as a sugar replacement. Almost 20 years ago I cut out all artificial sweeteners from my diet and lost 15 pounds in two weeks. At that time in my life that was the only change in my diet.
Artificial sweeteners mess with your body. I may not have the unassailable scientific proof that they are harmful, but I’ve lived it.
When I was on a low carb diet I drank tons of diet soda, and used Splenda instead of sugar. I lost about 40 pounds, and diet sodas never interfered with going into ketosis, which is what happens when your body starts burning it’s own fat instead of carbs. But I suppose if it’s combined with carbs it can make things worse. Still, I don’t think it’s as bad as sugar.