You make it sound like more fructose in a stomach will deliver a greater insulin response. If not, what did you mean by this statement?
Yes, obviously you need some glucose to be present in addition to the insulin.
Not following you. Insulin facilitates the metabolization of carbohydrates. When you consume glucose, insulin will be released.
You said earlier that a greater insulin response = more fat. What does that mean? A greater insulin response doesn't necessitate the creation of more fat. Michael Phelps eats a massive quantity of carbs when he is training yet he's about as ripped as you can get. Caffeine consumption spikes insulin levels but just because a person drinks caffeine doesn't mean they're going to get fatter.
Yes, my point (or really my conjecture since I’m no expert on this stuff) is that more fructose in the stomach can cause a greater insulin response. My point is not that metabolism of fructose can cause a greater insulin response. Fructose being in the stomach and fructose being metabolized are different, and it’s the former that I think might cause the body to respond with more insulin.
I don’t follow the sugar wars closely, but I think research has shown that it’s more than just the presence of glucose in the stomach that signals your body to produce insulin. There are other signals, including even the flavor of sweetness in the mouth, whether from sugar or not. I’ve experienced this personally (or at least I think I have) with artificially sweetened soda. I drink it and my blood sugar takes a nosedive. The explanation that seems sensible to me is that the sweet taste fools my body into releasing a shot of insulin, which results in the relatively small amount of sugar in my blood (since I haven’t actually consumed any sugar) being consumed by my cells so that not much is left behind, causing a sugar crash.
I think fructose in the stomach — not the metabolism of fructose where it is broken down into glucose but just its presence in the stomach as unmetabolized fructose — might be another such signal to the body to respond with a greater amount of insulin.
As for Michael Phelps and the rest — yes, I agree that at the end of the day it’s calories consumed versus calories burned that determines body weight. The catch is that an incorrect insulin response creates the possibility of a short circuit so to speak, where the sugar tends to go into fat storage rather than be available for activity. That seems like a not implausible explanation for those fat lab rats who were fed high fructose corn syrup rather than sugar.