Hi Bev - hmmm not sure about this one, I think Diet coke has citric acid in it which is a no-no. I do know that some people have the odd can of Coke Zero without it knocking them out of ketosis but I wouldn't dare - scaredy cat lol.
i would say that not diet coke as it has citric acid in it that can knock you out of ketosis. i used to drink an odd can 330ml of coke zero. when i first did the diet it was fine (did 780/790 plan, so long time ago), then last time i did CD i was doing ss and there was a debate to whether we should have it and finally it was said no! this time round it is a definite NO.
it's not the case of bubbles of knocking you out of ketosis or making you hungry as you can have fizzy water which is bubbly, with coke zero it is all about avoidance of things that we have in normal day lives. cd ss is supposed to be a complete break from it all.
having said all that..... if there is no way you can survive without an odd can once in a while then i personally (and i am not a cdc) would have one. if it means continuing with the diet or breaking it then have one.
i used to have an odd can last time round and i did this time round but i would never have more than 1 can a day and usually tried to stick to one sat and sun only.