Thursday, April 13, 2006

High-Fructose Hysteria

New York Times columnist Nicholas Kristof recently wrote a column comparing soft drinks to plutonium and anthrax. (The column is hidden behind Times Select so you will have to take my word for it.) The column is almost a parody of rational thought. Let's give it a thorough Fisking. Kristof begins by telling about the enormous human costs of obesity. He gives the annual death rate attributed to obesity as 125,000 per year. The figures given by the CDC are actually 25,000 and even this is a mis-statement. The CDC's study was on causes of death by factors associated with poor nutrition and sedentary lifestyle. This is not the same thing as obesity. Studies actually following individuals over time show that the health problems are actually associated with sedentary lifestyle. BMI has little affect on health among people with an active lifestyle (and yes, it is possible to be obese and active).

Kristof then moves on to sweetened drinks and high-fructose corn syrup. Instead of quoting a link showing that there is a link between the two he says:
There's also a circumstantial case against high-fructose corn syrup, because it began to be used widely in the 1970s, just when American stomachs started ballooning.
This is junk science at its best. Major aspects of everyday life have changed since the 1970s including the rise of cable TV, VCRs, and video games and an increasing reliance on eating out rather than home-cooking. Regardless, Kristof narrows his focus on a single ingredient.

Another point in Kristof's case:
Some studies indicate that the body metabolizes fructose differently from other sugars, so that the body is slower to get the message that it should stop eating.
He has more to say about how the body feels full. According to Kristof liquids do not contribute to feeling full. There are several issues at work here.

First, lots of foods are metabolized differently than other foods. That in itself means nothing. Second, you stop eating according to multiple factors. One is blood sugar level. Another is how full your stomach feels. Liquids do contribute to this, especially the second. Drink enough liquids and you feel bloated and lose your appetite. The third factor is how much is placed in front of you. This is the complaint about "super-sizing" - that people rely on serving sizes, not feeling full.

Finally, sweetened drinks are not the main source of calories in meals nor is it a new thing to consume liquid calories with a meal. Beer has more calories per serving than soft drinks and has been served with meals since pre-historic times. Socially, sweetened drinks replaced beer as a beverage.

The outstanding flaw in Kristof's column is that studies have been done on teenagers and soft drink consumption. The result was that a) teens do not drink as much soda as supposed, and b) there was no direct association between soda consumption and weight.

A further complication is that obesity is classified as a world-wide problem but other countries experiencing weight gain do not use high-fructose corn syrup. Where is their weight gain coming from?

But, not one to let facts get in the way of a good rant, Kristof proposed a tax of $.06/ounce on sweetened drinks. That works out to $.60 per can and would more than double the cost of a two liter. Strangely, he did not propose an exemption for drinks with artificial sweetener nor has anyone else who entered the debate. This is a telling point. Since it is supposed to be the sugar in these drinks that is the problem, why ban the versions with no sugar? For some reason, soft drinks anger a class of people who are only too happy to invent reasons for banning them.

For a different (but similar) take on Kristof's column, see here.

This article refutes the entire issue of childhood obesity. It also refutes a wire service story from a couple of days ago. According to the story:

Ninety percent of Americans know that most of their compatriots are overweight, but just 40 percent believe themselves to be too fat, according to a study published Tuesday.
[...]This confirmed the findings of a 2004 study by G. Rodriguez et al. in the International Journal of Obesity which found 42% of males and 32.1% of females classified as overweight or obese according to the BMI did "not have really high adiposity."
So more than a third of people who are classified as overweight according to BMI are not.

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