Hi Sue,

It is possible, it all depends on how many carbs you had in the days before starting, and how well you utilize carbs. I'm not doing atkins and have accidently gone into ketosis when having over 100 carbs(whole grain or legume carbs) and heavy exercise. If you were relatively low carb before starting - like under 150 then you could get into ketosis very quickly.

Have you worked out or done any cardio, this would cause the carbs to be used up more quickly and speed you into ketosis.