In that sense, sugar is like
alcohol. It’s got
calories, but it’s not nutrition. There’s no biochemical reaction that requires it. And at high doses, alcohol can fry your liver.
Same with sugar. Fructose, the sweet molecule in sugar, contains calories that you can burn for energy, but it’s not nutrition, because there’s no biochemical reaction that requires it. In excess, it can fry your liver, just like alcohol. And this makes sense, because where do you get alcohol from?