I think some people can get kicked out of ketosis due to caffiene
here's something i found
Does caffeine affect ketosis?
This is questionable. There ARE a few studies that suggest caffeine may cause blood sugar to rise, with consequent effect on insulin ... The studies involve consuming 50 gm glucose orally, followed by a dose of caffeine. This is quite different from a low carber, who is consuming only 20 gm carbs, in the form of high-fiber vegetables, spread throughout the day.
Many low carbers continue to enjoy caffeine-containing beverages with no serious impact on their weight-loss efforts. However, there are some sensitive individuals ... and persons who are extremely insulin resistant may need to restrict or even eliminate all caffeine. If you have been losing successfully then find your weight loss stalled for a month or two, and you are following your program to the letter, you might consider stopping all caffeine for a while, to see if that will get things started again.