Which is worse for your body: a diet soda or a regular soda?

Empirical evidence would seem to indicate diet soda is bad for you.   It fools you into believing you are making healthy choices when you are really just choosing to drink diet soda.   As a result most of the morbidly obese people you see drinking soda go with diet soda,  but still use it the same way they would regular soda.  Not so much as a beverage but as something to wash down a triple cheeseburger and a large order of fries.   Or as a chaser for a dozen donuts.  Actually it's not just the morbidly obese who do this.   The soon to be morbidly obese and the eventually going to be morbidly obese do it too.   I don't think it's any coincidence that the number of overweight people has increased annually since diet sodas were introduced.