Comment by jeffdavis

Clarification: sucrose is a molecule that quickly breaks down into one glucose and one fructose molecule, so it's basically 50/50 glucose/fructose. Fruit juice, honey, and HFCS are also about 50/50 glucose/fructose.

Almost all other carbohydrates break down into glucose and no fructose at all.

So one theory is that the fructose is especially bad. It is processed in a different pathway and might be a lot worse than the glucose pathway.