I have 2 big cups of regular coffee everyday with 1T. cream and 1/2 a sweetn'low in each and it hasn't kept me out of ketosis. I did try to give up coffee when I started atkins. I lasted about 3 months, but I missed it too much. I love having something warm in the morning and the caffeine gave my workout the kick that it needs. Maybe just switch to decaf at night...
Jenn