Are bottled smoothies as healthy as they claim?

[x-ray_vision]

@Saint_Cad

I was just reading that the issue with sugar is while glucose gets stored as glycogen, fructose gets stored as fat and so while we think of “fruit sugar” as healthy it is actually the worst kind.

There is all sorts of nonsense one can read. What you just claimed isn’t true. From the first link I posted:

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].

I’m obviously not in favor of replacing anyone’s daily fluid intake with soft drinks, but I can already see a number of straw man arguments headed my way. This is because people have a tendency to think in either-or terms that strictly involve extremes. I’ll quote an elegant review by independent researcher John White that echoes my thoughts [16]:

Although examples of pure fructose causing metabolicupset at high concentrations abound, especially when fed asthe sole carbohydrate source, there is no evidence that thecommon fructose-glucose sweeteners do the same. Thus, studies using extreme carbohydrate diets may be useful for probing biochemical pathways, but they have no relevance to the human diet or to current consumption.

More:

The Human Body Does Not Turn Sugar to Fat

The process of synthesizing fat from sugar is known as de novo lipogenesis—the new production of fat. This activity is highly efficient in some animals, such as pigs and cows—which is one reason they have become popular people foods—these animals can convert low-energy, inexpensive carbohydrates—grass, say, in the case of cows and grains for pigs—into calorie-dense fats.5 However, human beings are very inefficient at this process and as a result de novo lipogenesis does not occur under usual living conditions in people. Thus the common belief that sugar turns to fat is scientifically incorrect—and there is no disagreement about this fact among scientists or their scientific research.5-8

Under experimental laboratory conditions, however, where people are overfed large amounts of simple sugars, the human body will resort to converting a small amount of sugar into a small amount of fat (triglycerides) in the liver. For example, in one recent study, trim and obese women were overfed with 50% more calories than they usually ate—note, 535 of these extra calories each day came from four and a half ounces (135 grams) of refined sugar. In this forced-fed situation, the women produced less than 4 grams (36 calories) of fat daily from the extra carbohydrate.8 Extrapolation from these findings means a person would have to be overfed by this amount of food and table sugar every day for nearly 4 months in order to gain one extra pound of body fat from the conversion of sugar to fat—by de novo lipogenesis. Obviously, even overeating substantial quantities of sugar is a relatively unimportant source of body fat. (So where does all that fat come from?—the fat you eat is the fat you wear.)

The McDougall Newsletter