You aren't supposed to have it as it can make you hungry, however I do sometimes. I try not to do it too much, only when my breath is like unbearable lol, but then again I've always chewed a lot of gum (I'm a teenager so let me off!) so I may be used to the hunger feeling. It doesn't take you out of ketosis or anything either.
But the official CD word on it is don't do it, so best to stick away from it if you can. xxx