I was wondering will peanut butter or crystal lite take me out of ketosis? You said in a previous thread that aspartame might if that's the case how can I take a protein shake aren't they sweetened with it?
Peanut butter will kick you out of ketosis, only if too much is ingested: (ALL NATURAL) peanut butter has 6 carbs per 2tbsp...in turn, you cannot have more then
4-5 tbsp. a day. (I don't recommend having more, but some people can take more and stay in Ketosis, in my view it's not worth the risk)
Protein shakes are usually made with stevia (a natural sweetner that will not kick you out of ketosis) or another one, if I remember correctly is, splenda.
I also think Citric acid (found in many diet sodas) kicks some people out of ketosis, but doesn't affect everybody. Aspartame also seems to affect some people but it isn't consistent.