It’s not that I disagree with you or your cites, Epimetheus. I am just skeptical that fructose [as you seemed to imply] is a significant factor in causing obesity over straight glucose.
Glycolysis is generally the considered to be the first set of metabolic reactions the drives the energy-producing Krebs cycle and energy-storing lipogenesis (i.e. triglyceride production). It begins like this:
The last compound then enters the Krebs cycle or is used to form fatty acids.
Fructose can enter the reaction by being directly converted to fructose-6-P, bypassing glucose altogether. Given the same amount of glucose and fructose, the latter can be converted into acetyl-CoA just a tiny bit faster. But fructose metabolism is only a single step shorter in an extremely long series of reactions.
Now, what if you had a refreshing beverage made out of many parts of a plant, so that you would be able to drink it on the go and still consume a lot of vitamins and fiber? For instance, orange juice, pulp, seeds…
I agree, it is not a definate thing and there is debate even amongst nutritionalists, I only offered a reason that the person in the OP would take fruit out of the menu and offer vegetables instead. The fact that there is controversy over fructose. I personally still eat plenty of fruit.
