Monday, June 29, 2009
Photo by Dave_mcmt
A very interesting article came out this past week in the journal Obesity. Dr H Shelton Brown III and colleagues at the University of Texas School of Public Health examined how a child's assessment of their own body size (e.g. lean, overweight, or obese) is influenced by the body size of their classmates. Subjects consisted of male and female students in grades 4, 8 and 11. All students had their height and body weight measured, which were used to calculate their body mass index (BMI). This objective measure of obesity was then compared to the students' response on a questionnaire, which asked:
“Compared to other students in your grade who are as tall as you, do you think you weigh “The right amount,” “Too much” or “Too little(or not enough)”?
They found that for children in grades 4 and 8 (but not those in grade 11), a higher average BMI in their classmates was associated with a significant under-estimation of their own body weight. In other words, if an obese student was surrounded by overweight and obese classmates, they were more likely to estimate that they weighed the "right amount", rather than "too much".
It is interesting, and not terribly surprsing, that students assess themselves based on their peer group, rather than a scientific abstraction like BMI. I'm a distance runner, and many times I have heard people say that after being around other runners for several years, they start to think of a runner's body as the norm, even though it obviously is not (it's not surprising that disordered eating is quite high among distance runners).
This study is especially interesting in light of past research showing that obesity and other health behaviors like smoking tend to spread through social networks, which I blogged about here in one of my first posts last November. Could it be that individuals are less likely to address their own obesity if it is the norm for their peer group? Some have even suggested that targeting social networks, rather than individuals, may be the most effective way to prevent and treat obesity at the societal level. In fact, Dr Brown and colleagues suggest that interventions that focus on the school, rather than the individual, may be the best way to promote healthy body weights in children, and I think that it is a very reasonable suggestion (even though the Comments section on many of our posts suggest that many still feel obesity is about "personal choice", and nothing more).
This study adds to the growing body of evidence that obesity, as well as our perception of obesity, are influenced by those around us. If we want to see healthy behaviors in our society (and in our youth) as a whole, targeting individuals one at a time is probably not the most effective way to go about it. Interventions that target the school (or even better, the community) are the only way we are going to gain any ground against the current childhood obesity epidemic.
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Brown, H., Evans, A., Mirchandani, G., Kelder, S., & Hoelscher, D. (2009). Observable Weight Distributions and Children's Individual Weight Assessment Obesity DOI: 10.1038/oby.2009.168
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