(Reprinted from my personal blog, here) BMI can be an accurate predictor of health over a large population, but as I've previously written, it may not be a good indicator of individual health. Unfortunately, that's not stopping many school districts from using it as part of their PE curriculum, sparking a cost vs benefit debate that has yet to be adequately resolved.
I discovered that BMI was part of the national Presidential Youth Fitness Program the way many parents do: my child came home from school discussing his "number." (The program is a reinvention of the national Physical Fitness Test many adults remember from their childhood.) While our District had asked us to sign a waiver to join the program and asked us to purchase a heart rate monitor band, in the flurry of back-to-school paperwork, I missed the part that explained the use of this measure. Some school districts (fortunately, not ours) even go so far as to make BMI a part of students' PE grade, although that is not recommended by the program.
Beyond my concern about our national focus on body shape, I have additional concerns about BMI measurement in school programs. Studies have shown a possible correlation between disordered eating and messages from school programs. What's more, researchers at the Yale Rudd Center have shown that bullying or teasing about weight can actually cause adults and children to eat more, binge eat, and refuse to diet, and that students of all weights are more likely to be teased about their weight than for any other reason.
The Eating Disorders Coalition expressly recommends against BMI reporting in schools, and states that such reporting puts children at risk for developing eating disorders as well as for bullying. It cites an Arkansas study that showed adverse effects to in-school measurement. Arkansas, as a result of that study, determined that in-school BMI screenings were still valuable - but numbers are shared only with parents or guardians and kept private from children.
Although the PYFP is endorsed by the White House as a science-based tool, the CDC has expressed concerns about the use of BMI in physical fitness programs in schools, noting that "More evaluation is needed to determine whether BMI screening programs are a promising approach for addressing obesity among children and adolescents." The US Preventative Services Task Force notes that BMI is based on norms for Caucasian children, and its validity as a measure for minorities (who are at higher risk for negative health-related outcomes) is unknown. They also found that there is no direct evidence that this measure improves physiologic, behavioral, or health outcomes.
In 2009, the American Academy of Pediatrics released an article noting that "BMI screening does not currently meet all of the American Academy of Pediatrics’ criteria for determining whether screening for specific health conditions should be implemented in schools." and also that "Schools initiating BMI-measurement programs should adhere to safeguards to minimize potential harms and maximize benefits, establish a safe and supportive environment for students of all body sizes, and implement science-based strategies to promote physical activity and healthy eating."
If you are a parent and this post causes you concern, I urge you: raise your voice! Contact your school district, ask if they are using this measure, and how they plan to promote the program's main message that "physically fit and less-fit people come in all shapes and sizes" while still putting a target "zone" on BMI. Ask about school policies and infrastructure regarding accuracy, privacy, bullying prevention, and resources for families whose children are determined to be at-risk. Contact Fitnessgram and the Presidential Youth Fitness Program directly to express your concerns. Above all, have a conversation with your children, explaining that eating well and staying active is more important to their health than their size or shape.
(Please note: I know that this article is so link-heavy as to appear that I have been spammed. That is not the case: each link here is in lieu of a citation and leads back to the excellent studies and materials where I found the information. Please don't take my word for it - click through and read what the experts have to say.)