Hi there, mythirdeye. You can breath easy, fiber does not get absorbed by the human body. Be is soluble or insoluble it passes right through the GI tract and it should not effect ketosis. If anything it will help other meals that might contain carbs have less of an effect on insulin levels as it slows how quickly food empties from the stomach.

We have a nutrition and supplements forum where you can find lots of information on fiber if you're interested. The most important thing to remember when taking fiber is that you should take it 2 hours before or after you take any other supplements as it can effect their absorption. Always have a big glass of water with your fiber supplement - too little water w/ too much fiber will have the opposite effect.

HTH
Nat