Okay, I watched it, and it's a terrific presentation, but I do think that Aragon has a few valid criticisms. Dr. Lustig confused me a bit of the way through, because he abstracts fructose from its glucose counterpart when he talks about sucrose metabolism. First he talks about glucose metabolism, and then in an attempt to equivocate fructose to ethanol, talks about ethanol. He then discusses sucrose up to the point where half of the molecule is fructose, then goes on to talk about fructose metabolism, but this is a problem.
He's jumped from sucrose metabolism to discussing PURE fructose metabolism, effectively leaving out what the glucose side of the molecule does while fructose is being metabolized. The larger portion of his argument (fructose's alleged behavioral effects) rests on the rather large assumption that metabolizing 1/2 of the calories from fructose from a beverage will have the same effects as if all of the calories were from fructose (Aragon's dose criticism). That seems like a rather large leap to me. Moreover, it's not as if metabolism of these sugars is occurring one by one time, they are occurring in parallel (though perhaps not at the same rate). So while the glucose is driving certain reactions, fructose is driving other physiological processes as well. What is the net effect of this parallel-processing effect? He never specifies.
It seems overly simplistic to first, discount the multiple effects of other molecules on fructose metabolism (and subsequent behavior) and second, to discount the dose at which these things occur. That is a HUGE flaw. His presentation leaves you thinking that a bit of fructose will automatically lead to all of the grisly consequences of fructose overconsumption.
A few more criticisms, from my own experience of how people actually eat: Lustig takes all of the humanity out of eating and makes us out to be slaves to our hormones. We have all had the experience of "finding more room" to eat a slice of pumpkin pie after stuffing ourselves full of turkey and cranberry sauce. People with Alzheimer's dementia inexplicably "forget" to eat - or sometimes, as I've seen forget that they've just eaten and eat again. I can't leave food around my computer because I will absentmindedly eat it. I went through 1 lb of almonds in 4 hours this way once and paid the price some two hours later. Some of us eat multiple times during the day out of habit, others do as a compensatory reaction to stress or fear. As humans, we can clearly override our satiety signals. Additionally, Lustig has oversimplified satiety in this presentation - it's not just leptin that causes in satiety, there are a bunch of more hormones (such as peptide YY and alpha-melanocyte stimulating hormone) that promote satiety as does insulin. It's not as simple as one hormone going up, the other going down and wham! Obesity.
I'll also comment that Dr. Lustig seems to have overreached beyond his medical expertise a bit with his "Japanese diet contains no fructose" statement. I'm Japanese, and the Japanese diet has plenty of sucrose if you look for it, they produced it from sugar beets. As Aragon mentioned, there is plenty of fruit native to Japan as well. Where Lustig *may* be on the money, however is that the traditional Japanese diet contains vastly less refined sugar in comparison to the traditional American diet. I'm with Aragon. It isn't as cut and dry as Lustig explains it, although he certainly does make a compelling case.
I would also make a general criticism that employing "master theories" in explaining away what are in appears to be a more complex phenomenon is a bit simplistic, because obesity is a social, economic, and political issue (let's not get into issues of environment, urban planning, demographics, genetics, etc., which further complicate the matter). Lustig does touch on these, but I think that he would try to attribute the increase in average calorie intake to the introduction of large amounts of fructose into the food system, rather than the fact that the Farm Bill drove down prices of commodity crops across the board, which in turn drove food prices down. It's not just corn - wheat, rice, soybeans and cotton are also commodity crops, and the farm bill contains massive subsidies for these (this is essentially Dr. Marion Nestle's argument - a nutritional biochemist and public health advocate interested in the politics/economics of food). This may be because he's a physician, and not an economist, that he is inevitably going to look for a metabolic etiology to the problem, whereas an economist would subject obesity to economic analysis. Dr. Brian Wansink, a psychologist, has also done studies at his Cornell lab that show how visual cues can trick people into consuming more calories than they consciously realize (a concept termed "portion distortion." All of these people are pointing in the same direction, and I think that they're all right. But it seems to be a mistake to say that only one of these theories is true, because obesity is one hell of a lot more complicated than that. If you spent the time to finished reading my really long post, good for you.
P.S. Lustig seems to have quite the penchant for conspiracy theories, as well...or is it just me?
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