Can anybody debunk/source this? It makes sense in a way, but also sounds a bit like voodoo science... the original poster didn't cite a source, and it's on a private forum so I can't link to the thread, sorry.
It's important to understand that fructose is isocaloric but not isometabolic. This means you can have the same amount of calories from fructose or glucose, fructose and protein, or fructose and fat, but the metabolic effect will be entirely different despite the identical calorie count. This is largely because different nutrients provoke different hormonal responses, and those hormonal responses determine, among other things, how much fat you accumulate. This is why the idea that you can lose weight by counting calories simply doesn't work...
Fructose is metabolized primarily by your liver, whereas glucose is metabolized in every cell of your body.
Every cell in your body, including your brain, utilizes glucose. Therefore, much of it is "burned up" immediately after you consume it. By contrast, fructose is turned into free fatty acids (FFAs), VLDL (the damaging form of cholesterol), and triglycerides, which get stored as fat.
For example, when you eat 120 calories of glucose, less than one calorie is stored as fat. 120 calories of fructose results in 40 calories being stored as fat. Consuming fructose is essentially consuming fat.
Also, glucose suppresses the hunger hormone ghrelin and stimulates leptin, which suppresses your appetite. Fructose has no effect on ghrelin and interferes with your brain's communication with leptin, resulting in overeating.