I have been told coke zero is fine hun, I drink prob 3 cans a day... Although - be warned, it may make u feel hungry/gassy. It won't take you out of ketosis cos its got malic not citric acid in it, but may make u crave food. It does with me from time to time but I am ok with it. I've left home quickly and forgotten a few times too, thats why i tend to keep a tetra in my bag now