Do not count fiber as calories or carbs.
There is a common mis-conception that fiber is "carbs that cannot be digested." This is incorrect; eating something that can't be digested - say, a matchbox car - is painful and maybe damaging.
Fiber is digested, but cannot be ABSORBED across the intestinal lining. Fiber does not increase insulin (in fact blunts insulin effect of absorbable carbs), and is not available as calories.
[On a related note, there is an amount of each nutrient that is optimal; less is "deficiency", more is "toxicity". For fiber, for most people, that amount is about 15 g per day. Conventional wisdom says a lot more, conventional wisdom is wrong. The other things you need for pooping are: water, walking, magnesium, digestive enzymes, probiotics. More fiber is not always better.]