Look, the reality is that if you still drink diet soda, I don’t think the “it’s really bad for you in general” Responses are what you’re looking for or are going to be so convincing for you to not drink it. If you don’t know that diet soda isn’t good for you by now, you’re living under a rock. You probably know that already and do still indulge. You’re human. I get it. So, supposedly, diet soda can slow loss because your body has an insulin response to it. I drank Diet Coke occasionally, it never slowed my loss. However, some other people have reported it has slowed theirs. You’re going to have to try and see. However - it IS super bad for you, so if you can cut it out, great.