Whilst sugar is more specific than "chemical" it's still a pretty broad term, there are plenty of non-metabolizable oligosaccharides out there that none of your cells can use for respiration. And there are a couple that are generally non-metabolizable or processed at a low rate, but certain types of cancer uptake and process at a much higher rate (a fact used in some cancer treatments to help target said cancer cells specifically). Those could cause relative tumor proliferation in the bizarre situation where high proportionate consumption of those oligosaccharides is paired with a state of general starvation.

But again, being ignorant of the technical specifics does not automatically make one incapable of understanding or making rational judgements, just unfamiliar with the subject.