In 30 years of practice when this comes up I tell my patients I've never admitted a patient to the hospital due to diet soda, I've never written a death certificate with diet soda as cause of death. But obesity? Diabetes? Too numerous to count. That said, how about a nice glass of Poland Spring Water? A quote from another doctor.
Yes there are limited studies that argue that artificial sweeteners are also bad. So my focus is on people who are looking to lose more body fat and would like a soda. If you don't care for stevia or seltzer water with a splash of juice and want more than water, then this seems like an occasional treat that keeps you on the path of developing a healthier diet.