"There are only two ways of telling the complete truth—anonymously and posthumously."Thomas Sowell

Wednesday, October 19, 2005

Why Johnny Is Fat

In a recent article on Tech Central Station, health-policy writer John Luik provides an excellent analysis noting that the real cause of the rise in childhood obesity in recent years is infrequency of physical exercise, not dietary problems. Luik writes,

[A] recent Canadian study looked at the eating and physical activity habits of 4,298 school children in an effort to determine which risk factors were important for overweight and obese children. The researchers included questions about whether the children ate breakfast, whether their lunch was brought from home or purchased at school, how often they ate in fast-food restaurants, whether there were regular family dinners and whether dinner was eaten in front of the television.

The results are startling, for they disprove so much of what passes for contemporary "wisdom" about childhood obesity. First, eating in a fast-food restaurant (which according to the Fat Police is the major source of childhood obesity) was not statistically significant as a risk factor for obesity, even in children who eat in such restaurants more than three times a week.

Second, the study found that there was not a statistically significant difference between the quantity of fizzy drinks consumed by children attending schools that did not sell fizzy drinks and those that did. Children in schools that sold fizzy drinks consumed an average of 4 cans of soda per week, while children at schools which did not sell fizzy drinks consumed 3.6 per week. This works out to 33.5 and 32.5 grams of sucrose per day, with the extra gram adding four calories for the kids where fizzy drinks were sold—an insignificant amount in terms of total daily caloric intake.

Third, there was not a statistically significant association between the availability of fizzy drinks at schools or schools with food vending machines and the risk of children being overweight or obese. As the authors noted: "We observed that children attending schools that sell soft drinks consumed somewhat more soft drinks and sugar, but the amounts were likely insufficient to bring about differences in body weight."

In addition to this, research shows that kids who are normal in weight actually eat more "junk" food than their overweight peers. Luik cites a World Health Organization study released this summer which found that in "91% of the countries examined, the frequency of sweets intake was lower in overweight than normal weight youth." The study found a "negative relationship between the intake of sweets (candy, chocolate) and BMI classification in 31 out of the 34 countries such that higher sweets intake was associated with a lower odds of overweight," in the words of the study report.

This means that children who eat more junk food are actually less likely to overweight than their peers. In addition, the study found, "Overweight status was not associated with the intake of fruits, vegetables, and soft drinks."

Luik points out that these studies confirm the conclusions reached by countless earlier ones, some of which he cites, and he notes that their conclusions regarding physical activity are as follows:

While the Canadian study and others have failed to find a connection between fizzy drinks and childhood obesity, they have found a striking association between obesity and children's physical activity levels in general and the frequency of physical education classes at their schools in particular. "Children attending schools with more frequent physical education classes," they write, "were increasingly more likely to have normal body weight."

As for physical activity in general, they note that "frequency of physical activity appears to be the only activity-related factor independently associated with overweight."

Despite this clear evidence, however, schools continue to cut back on physical education classes while concentrating on getting "junk" food out of their cafeterias. The latter may well be a good thing to do, but it has virtually no effect in reducing childhood obesity. Educators should stop thinking so much about the cafeteria and vending area and should get the kids into the gyms and on the playgrounds.


Tlaloc said...

Despite TCS contention that diet is not a factor if you actually read the report they don't say that at all. The following are excerpts from the report which you can find here.

"We found that children from families that eat together regularly are less likely to be overweight or obese. One reason for this is that these children generally eat a more healthy diet.25,30,31"

"Previously we showed that integrated school programs that include more physical education, healthy lunches, health and nutrition education, training of staff, parental involvement, and a halt to the sales of soft drinks were successful in improving children's diets and reducing overweight by 59% and obesity by 72%.24"

"With respect to sociodemographic factors, children whose parents had attained higher levels of education and had an income over $60 000 were at a decreased risk of overweight, as were children who resided in urban areas and who resided in neighbourhoods where the income was in the middle or highest one-third (Table 3)."

(it's well known that the food available to those on a tight budget os of vastly inferior quality to that enjoyed by the middle and upper class, if you don't believe me try reading the health information on Ramen sometime)

Furthermore some of the other findings that TCS seems to find so pertinent really don't mean what they say they mean. For instance they say that those kids who eat at the school are 12% more likely to be obese but the number isn't statistically significant. TCS reads this as "eating unhealthy school lunches doesn't contribute to obesity." That's simply wrong. The correct interpretation is "This study showed a connection but the sampling size was too small to bear out whether it was real or a function of noise."

Kathy Hutchins said...

it's well known that the food available to those on a tight budget os of vastly inferior quality to that enjoyed by the middle and upper class, if you don't believe me try reading the health information on Ramen sometime

If you're relying on ramen for your basic nutrition, the problem is not that you're poor, it's that you don't know how to cook. I went to graduate school in Texas. Since the size of my stipend relegated me to a rental duplex in a Tejano ghetto, I took the opportunity of learning to cook from my neighbors. Even now, adjusting for inflation, I could feed myself not only an adequate, but a more healthy diet than most middle class Americans eat, for fifteen dollars a week.

The secret, of course, is learning to like beans. Lots of beans.

You can even make ramen better, you know. A brick of ramen = $.08 (they're always on sale here somewhere 12 for a dollar). One hard boiled egg = $.06. A handful of bok choi or water spinach from an oriental grocery = $.05 or so. Less than 20 cents for a meal, less than a quarter even counting the energy to cook it, and it's not that malnutritious. It's kinda fatty, cause the noodles are fried. Other than that, I don't see the problem.

Bookworm said...

Ah! If only I liked beans. Fortunately, my children and I like a variety of other healthy (albeit not that cheap) foods. Also fortunately, my children are active by inclination, and we live in a community that enables them to, well, act on that activity.

Interesting article, and one that makes me feel less guilty about occasional trips to In 'n Out.

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