TCS Daily


Some Rare Good News on the Obesity Front

By John Luik - November 8, 2005 12:00 AM

Most days the headlines about fat, filled as they are with the latest "study" on the dangers of obesity or the newest crazy proposal about preventing it, rarely make for encouraging reading. That's because so much of what passes for obesity science has a large element of junk science in it, whether it's about the supposedly 400,000 Americans who die from being overweight each year (false) or the claim that consumers of French fries are likely to get cancer from acrylamide (false). So it's good to discover some "fat" stories that provide a bit of balance in understanding just what might be driving weight gain in Americans.

The stories come from research presented at the recent annual conference of the North American Association for the Study of Obesity (NAASO), which was held this year in Vancouver, British Columbia. The stories didn't, of course, make the front page for while the media did not exactly ignore the obesity research conference, its coverage was hardly what one might call serious. For example, about the only bit of research that received national coverage was how losing weight could do wonders for your sex life. But even if they didn't make the front page, they are worth understanding since they confound so much of contemporary wisdom about what about to do about obesity.

The first paper ("Frequency of School Vending Machine Purchases, BMI and Diet Quality") looked at the frequent claim, made most recently by the Terminator, that school vending machines are responsible for making kids fat and should be banned. The study looked at the differences between how frequently kids used school vending machines and their body mass index (BMI) and diet quality. The subjects were 552 high school students who were surveyed about their diet quality, including total calories, total fat, saturated fat, total carbohydrates and sugar, and their vending machine purchases.

The subjects were divided into four groups based on how frequently they used their school's vending machine in the past thirty days -- with one group of those who did not use it at all or purchased only water, another group which purchased 1-3 items, a third group whose members bought 4-6 items and a final group whose young people bought more than six items. The most frequently purchased item from a vending machine, according to the authors, was not pop but water, purchased by 36.3% of the young people, followed by sweetened beverages other than pop purchased by 31%.

But what was really interesting was that there were no differences in BMI percentile or in calories between the four groups. In other words, contrary to the claims of those who blame school vending machines for childhood obesity, vending machine purchases did not make a difference to the student's calorie intake or to their BMI. As the authors conclude the "Results suggests that frequency of purchase from school vending machines was not associated with BMI percentile or DQ [Diet Quality]."

The second study looks at another of the popular obesity claims, namely that the portion sizes offered by restaurants make people fat. Indeed, some fat activists have even called for the government to regulate portion size. In this study ("Does Portion Size or Amount of Food Affect Consumption?"), what the researchers wanted to test was the claim that large portions lead people to eat more food. What they found was that portion size made no difference in the amount of food consumed. Participants who had received large portions did not eat more food than participants who had received small portions, even though their portion contained five times more food. The availability of the extra food did not influence total consumption. As the authors note "There was no effect of portion size" which "suggests that smaller portions did not influence intake...."

Neither of these two studies should come as a surprise for they confirm a considerable amount of previous research about students, vending machines, soft drinks and fast food restaurants. For example, a recent Canadian study that looked at the eating habits of 4,298 school children found that eating in a fast food restaurant was not a statistically significant risk factor for obesity, even for children who eat in these restaurants more than three times a week.

The same study also found that there was not a statistically significant difference between the quantity of soft drinks consumed by children attending schools that did not sell soft drinks and those that did. Additionally, it concluded that there was no association between the availability of soft drinks and schools with vending machines and the risk of children becoming obese.

In short, these three studies provide good reasons to reject not only the soft drinks+ vending machines=obesity thesis, but also the claims of the fat police that portion sizes promote obesity. And coming in the same week that the U.S. House of Representatives passed the Personal Responsibility in Food Consumption Act by a margin of 306-120, which would prevent the country's trial lawyers from suing restaurants and the food industry for allegedly making people fat, it was all in all a good week for sound science in the service of responsible public policy.

John Luik is writing a book about health care policy.

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