What it is
Glucose-based syrups and sugars — corn, rice, and tapioca run down to their sugar. The structural glue holding industrial recipes together, cheaply.
Why your biology objects
Almost pure glucose, so there's no fructose-to-the-liver problem here — the issue is the other axis: these are fast, fiber-free sugars that spike blood glucose sharply (glucose syrup's glycemic index runs near 100). Energy with nothing attached.