January 5, 2004
Fast Food Study Over-Hyped
Does fast food cause childhood obesity? Judging from the coverage of a recently published study, the media certainly thinks so. The study's primary author, credentialed food activist David Ludwig, makes every effort to blame fast food restaurants for pudgy youngsters. But there's no there there. Ludwig's results range from the obvious to the unimpressive.
Ludwig's primary conclusion is that kids' diets suffer when they eat fast food. But the numbers can't justify the hype. Ludwig found that children (aged 4-19) who eat fast food or pizza in a given day take in an average of 8 or 9 more grams of fat, about the quantity in a glass of milk. They consume an average of 187 additional calories, which is equivalent to less than a cup of lima beans. And Ludwig's figures are significantly smaller for younger age categories: four- to eight-year-old children who eat fast-food or pizza apparently ingest enough extra calories to account for a single plum. Horrors.
Ludwig reports that "children eating fast food obtained a mean of 29% to 38% of total energy from fast food." Translation: kids who have a fast food meal get an average of 1/3 of their calories from it. Considering that there are three meals in a day, this is hardly the stuff of headlines.
Ludwig also tells us that 30.3 percent of children eat fast food on a given day. That's made to sound like a lot, but all it means is that the average American kid grabs a slice of pizza, a burger, or some to-go chicken two or three times a week.
Ludwig admits that his study "relies on self-report of intake (assisted by adult household members of young children), a dietary assessment technique that may be inaccurate and imprecise." And a study referenced by Ludwig reveals that 46 percent of kids over-report their food consumption.
The biggest problem is that Ludwig failed to correlate his central findings with the actual body weight of any children. Not a single kid's weight made it into Ludwig's paper. Are children who eat fast food more likely to be overweight? Ludwig doesn't say. For a man who co-authored (with big brother Kelly Brownell) an op-ed comparing obesity to a massive SARS outbreak, that's quite an omission.
What Ludwig does say -- it is, in fact, his concluding sentence -- is that his results somehow mean that fast food marketing should be restricted. This is Ludwig's only policy suggestion, and it is a bizarre one, considering that his analysis has nothing whatsoever to do with marketing. But it is what we've come to expect from Ludwig, who is most famous for a soda-bashing study which trumpeted claims that the data did not support. And it's no surprise for a paper that began by referencing anti-food-business fanatics Eric Schlosser and Marion Nestle.
