This all being said my kids came to the right place! I love to bake and now can just skip the margarine and applesauce low fat replacement recipes and go straight for the cream cheese extra's and caramel sauce. Clearly I cannot consume the amount of these treats that I hope my kids do (sometimes I do though, woops) but the point is I have had kitchen role-models to follow that have showed me how to make some awesome stuff. So the answer we give is "YES! You absolutely can have a second slice of cake! Good job buddy!"
------Side note of further enzyme explanation-----------
A CF pancreas is blocked from releasing natural enzymes by their thick CF mucus so they take prescription enzymes to aid in more of a normal digestion process. Still though the enzymes they take when they eat do not make up 100% for the bodies lack of natural enzyme release.
The amount of enzymes a CF person needs is calculated by their age, weight, and other growth factors combined with any malabsorbtion symptoms they are experiencing (pain, BM issues, etc). Adults with CF can even get to a point that they "max out" with the amount of enzymes they need compared to how many is safe for them to take.
So even though a CF person takes enzymes their stomach is often sore and hurting. Knowing that their digestive process would never be 100% comfortable I am exceptionally sensitive to when the kids say their stomachs are bothering them. The kids talk about their stomachs hurting often. I hate it because I can't see it to fix it. It's not a skinned knee or a sore ear, I can't get an antibiotic for it - it just hurts because that is how their body feels even when it is doing its best to function.