Well your body isn't fully converted over to the ketones as fuel until about three weeks in. So screwing around with too many carbs (more than 100) in this time period could have negative effects.
That's why on many cyclical diets there is an initiation period. This initiation period is so your body can shift its fuel usage more towards FFA and ketones.
I totally recommend re-feeds (on clean foods) worked in with ketogenic diets, but not within the first couple of weeks.