Fructose is evil, context be damned
So, is fructose really the poison it's painted to be? The answer is not an absolute yes or no; the evilness of fructose depends completely on dosage and context. A recurrent error in Lustig's lecture is his omission of specifying the dosage and context of his claims. A point he hammers throughout his talk is that unlike glucose, fructose does not elicit an insulin (& leptin) response, and thus does not blunt appetite. This is why fructose supposedly leads to overeating and obesity.
Hold on a second…Lustig is forgetting that most fructose in both the commercial and natural domain has an equal amount of glucose attached to it. You'd have to go out of your way to obtain fructose without the accompanying glucose. Sucrose is half fructose and half glucose. High-fructose corn syrup (HFCS) is nearly identical to sucrose in structure and function. Here's the point I'm getting at: contrary to Lustig's contentions, both of these compounds have substantial research showing not just their ability to elicit an insulin response, but also their suppressive effect on appetite [3-6].
But wait, there's more. In studies directly comparing the effect of fructose and glucose preloads on subsequent food intake, one showed no difference [7], while the majority have shown the fructose preload resulting in lesser food intake than the glucose preload [8-10]. A recent review of the literature on fructose's effect on satiety found no compelling case for the idea that fructose is less satiating than glucose, or that HFCS is less satiating than sucrose [11]. So much for Lustig's repeated assertion that fructose and fructose-containing sugars increase subsequent food intake. I suppose it's easier to sensationalize claims based on rodent data.
In the single human study I'm aware of that linked fructose to a greater next-day appetite in a subset of the subjects, 30% of total daily energy intake was in the form of free fructose [12]. This amounts to 135 grams, which is the equivalent of 6-7 nondiet soft drinks. Is it really that groundbreaking to think that polishing off a half-dozen soft drinks per day is not a good idea? Demonizing fructose without mentioning the dose-dependent nature of its effects is intellectually dishonest. Like anything else, fructose consumed in gross chronic excess can lead to problems, while moderate amounts are neutral, and in some cases beneficial [13-15].
