I switched to diet coke ab 6 months ago from regular soda. One 20oz bottle daily. Is that bad? Any long term effects?? Don't drink don't smoke.

Good start! You are doing yourself a favor switching from regular Coke to Diet Coke, because you will take in fewer calories in the long run. However, You are still taking in quite a few artificial ingredients with Diet Coke. Want to be healthier? Try to begin having a day here and a day there where you eliminate the soft drinks altogether. Eventually, you may be able to quit. Good luck.