Thursday, September 13, 2012

Study Reveals Overweight Teens Have Fewer Arms Than Healthy-Weight Ones

A truly shocking study published today ahead of print in the journal Pediatrics revealed that overweight teens reported having one fewer arm than their healthy weight counterparts.


(I'm sighing a lot these days).

No, overweight teens don't have fewer arms than their healthy weight counterparts, and I'm equally doubtful that overweight teens eat fewer calories than so-called healthy weight teens either, yet that's what's been trumpeted all over the media and blogosphere for the past few days.

The reporting stems from a paper entitled, "Self-Reported Energy Intake by Age in Overweight and Healthy Weight Children in NHANES, 2001-2008". In it researchers detailed the "surprising" finding that overweight and obese girls over age 7, and overweight and obese boys over age 10 reported consuming fewer calories than their healthy weight peers.

What I find rather amazing though is that the researchers, rather than focus on the story being overweight girls as young as 7 and boys as young as 10 may have already suffered sufficient societal stigma to under report their dietary intake when asked how much they're eating, instead decided to conclude that contrary to what the laws of thermodynamics require, overweight kids and teens either have created for themselves a, "self-perpetuating" state of obesity, or that they're significantly less active.

Now to be fair they also mention a third possibility, that perhaps overweight kids under report their dietary intakes, but then they explain why they think that isn't the case.

So is there evidence out there suggesting that overweight teens are in fact the world's worst dietary historians?

Why yes there is.

In February of last year there was a review paper published in the International Journal of Pediatric Obesity titled, Assessing dietary intake in children and adolescents: Considerations and recommendations for obesity research. Regarding under-estimation, here's what the review paper's authors had to say,
"One of the most robust findings in dietary studies of children and adolescents is the positive association between under reporting and increased body fatness, particularly in adolescents (4,14,15). This is consistent with studies in overweight and obese adults (16). The extent of mis-reporting irrespective of weight status increases with age and has been reported as 14% of energy intake in 6-year-olds (17), 25% in 10-year-olds (18) and 40% (4,19) to 50% (14) in obese adolescents.."
The authors further report that the type of study most likely to suffer from under-reporting is the very type performed here,
"Studies characterising under-reporting have focused on total diet assessment methods and in particular, energy intake"
So let me ask you a question.

If we knew that when polled obese teens under-reported their number of limbs by 50% do you think it'd be wise to take their reporting at face value and come up with theories as to why one of their arms fell off, or would it be more useful and important to try to understand the drivers that led those teens to misrepresent their limb status'?

Sir William Osler one of the founders of modern medicine once said,
"When you hear hoof-beats think horses, not zebras"
The horse is under-reported calories. Moreover it's a horse that's been spotted many times. To ignore that horse and instead focus on one-armed teen zebras? The only explanations for that behaviour I can come up with are ignorance, or willful misrepresentation in the name of publication or publicity - and neither are pretty.