The main substance that burns but doesn’t necessarily get metabolized is dietary fiber, which is a category of some different polysaccharides that burn but don’t get (fully) digested.
So high fiber foods would tend to give incorrect results in bomb calorimetry.
Are nutritional/digested calories actual equal to their combustion energy?
It’s within a percent.
The main substance that burns but doesn’t necessarily get metabolized is dietary fiber, which is a category of some different polysaccharides that burn but don’t get (fully) digested.
So high fiber foods would tend to give incorrect results in bomb calorimetry.