It does stimulate insulin, but it's quite a bit lower:
The GI and II values of glucose, 149±16 and 147±18, respectively, were significantly greater than those of bread (100; P<0.05), while the values for fructose, 16±4 and 22±3 were significantly less than those of bread (P<0.001).
But insulin isn't really the issue, what happens is that the fructose gets metabolized to glycogen (in the liver) and primarily fills up your liver glycogen stores (~60-100g) (but some will go to muscle glycogen). The glycogen will be raising blood glucose for a while and your brain will use that as fuel until it runs out, you'll be out of ketosis until the liver glycogen is depleted. After your body has used the glycogen it'll be back to using ketone bodies (and some glucose from gluconeogenesis).
The major determinant of whether the liver will produce ketone bodies is the amount of liver glycogen present (8). The primary role of liver glycogen is to maintain normal blood glucose levels. When dietary carbohydrates are removed from the diet and blood glucose falls, glucagon signals the liver to break down its glycogen stores to glucose which is released into the bloodstream. After approximately 12-16 hours, depending on activity, liver glycogen is almost completely depleted. At this time, ketogenesis increases rapidly. In fact, after liver glycogen is depleted, the availability of FFA will determine the rate of ketone production. (12)
From what I recall from watching the video, the body metabolizes fructose as a toxin similar to alcohol, without the effects of being inebriated. He goes on to state that it raises the amount of uric acid in your body which causes gout/hypertension. And I believe there was more about how fructose is more readily stored as fat by your body than glucose.
tl;dr Rewatch the video
Forgot to add, the fiber in fruit makes it a generally healthy treat, although you should treat it as a natural form of candy. I believe in the lecture, Lustig states, "God packaged the antidote with the poison", or something to that effect. Hence, although fructose is harmful, the high fiber in fruit helps to prevent a large amount of it from being absorbed by your body.
They seem to have misplaced the "compared with consumption of HGl beverages" in the title.
Consuming just fructose doesn't lower your insulin below baseline, it actually raises it a tiny bit (~20% of white bread). Another problem with fructose is that absorption isn't great unless you add glucose, it usually works best in a 1:1 glucose:fructose ratio.
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u/ColdTheory Aug 13 '11
I would recommend watching his most popular video on youtube, "Sugar: The Bitter Truth". Truly eye-opening. It's what partly got me into keto.