I would suggest avoiding diet soda, even if it has no caffeine or sugar.
Artificial sweeteners like aspartame are a cause for concern. It has been linked to various conditions but especially hyperthyroidism , which they found in my blood tests. Not wanting to go through the thyroid-killing treatments for that (treatment for hyperthyroidism often makes you permanently HYPOthyroid). I have decided instead to avoid aspartame, and then see what happens.
Another more minor concern is the overly acidic nature of the drink (not from the carbonation, but adding phosphoric acid) which can erode tooth enamel over time.
I don't want to drink soda until these companies switch to using stevia. Stevia doesn't have the calories of sugar or HFCS, but it also isn't some chemical unhealthy toxic crap.
I've been without diet soda for 22 days, drinking only water, and occasional fruit juice.....I used to be addicted to diet soda, it was all I drank. And so I imagine I have consumed a lot of aspartame. But now I have a reason and I am sticking to it.
I don't know why they are promoting Truvia so much but they still stand by aspartame and sucralose in diet soda, it makes no sense. There is a new soda called "Zevia" but it is too expensive and inconvenient.
Anyway I heard about the new gadget "Sodastream" which carbonates water. They sell flavorings with sucralose in it though. But you could probably buy fruit flavorings (lemon/lime extract? and other fruit) yourself and add them, and then add Truvia. That would be cool....I have to get a sodastream.