Yes, there is much evidence pointing to toxic build up of aspartame in the system that can cause neurological symptoms! One woman apparently was diagnosed with MS because of it and lost the ability to walk on her own, and was still drinking loads of Diet Coke and when she stopped, she was so much better after a week or so, up and walking and feeling fine!

The best thing for your body, if you do not want to drink calories, is just water. Or water down juice, or mix seltzer and juice to make "soda." I find that I have more headaches when I ingest artificial sweeteners, and it is a known migraine trigger.