MzKiki - I'm not a nutritional expert, but I will say that it isn't so important what you "ingest", but what you "absorb". If you, for one reason or another (illness, drugs etc.) your body isn't actually using the calories, like with "resistant starch" (though I have no idea if that's a real thing!), they they aren't going to be turned into fuel and potentially fat by your body.
One that I know is legit is the sugar alcohols. Our bodies will absorb some of the carbs from them, but they are used for diabetic candy, because they aren't absorbed totally and they are absorbed slowly. But there is a warning on there that if you eat too many of them at a time, you will have bowel problems - they go right through your system without stopping.
So, even though the most accurate way to measure what we are getting is by what we eat, that may or may tell the whole story if all of what we eat isn't actually making into our bloodstream. I am pretty confident that if you don't eat a calorie it won't make it in though (though there are some days I wonder!).
"You don't have to be perfect, you only have to do better." - Kaplods (3FC Sage)