In 2002, the Arkansas state legislature passed a law requiring the state board of education to "promulgate appropriate rules and regulations" making it obligatory for all schools in the state to include as part of a health report to parents an annual body mass index percentile by age for each student. Arkansas schools were to be given part of the funds from a national tobacco settlement to carry out the new mandate.

That made Arkansas the first state to require body mass index (BMI) percentiles as part of student health records. One of the officials charged with carrying out the legislature's mandate reported this month on what has happened in Arkansas since the law was passed.

Joy Rockenbach of the Arkansas Center for Health Improvement noted that the 2002 law actually called for more than annual BMIs for students. She pointed out that the law, Arkansas Act 1220, also eliminated all vending machines in elementary schools, required professional education of all cafeteria workers, required public disclosure of "pouring contracts" between schools and soft drink manufacturers and distributors, and mandated parent advisory committees for all schools.

But at a time when four more states are under instructions from their legislatures or state boards of education to conduct body mass index screening, and two states are doing so under mandates from their state health departments, Arkansas' experience with BMIs may be helpful to others, Rockenbach believes.

For one thing, it became apparent very quickly in Arkansas that there was need for uniformity in procedures if height and weight were to be measured in the same way everywhere. Part of the tobacco money was used, therefore, to buy scales and instruments to measure stature, which were distributed to all schools in the state. The results of those measurements—conducted in almost all cases by school personnel, rather than parent volunteers, in order to protect student privacy—are fed into a central computerized calculator.

The statewide figures generated for the first two years of the BMI program show that in school years 2003 and 2004, the numbers of students classified as "overweight" in Arkansas ranged from 72,636 to 77,351 but remained at or close to 21 percent of all students. The number of students found to be "at risk of overweight" grew from 59,503 to 63,943 but remained in both years at 17.2 percent of all students. That left from 60 percent to 60.1 percent of students "healthy," meaning they were neither overweight nor underweight, with another smaller group (1.8 percent to 1.9 percent) of students classified as "underweight."

When analyzed by gender and ethnicity, the Arkansas figures show Caucasian males slightly more at risk than Caucasian females for overweight or risk of overweight; Hispanic males more at risk than Hispanic females; and African-American females considerably more at risk of overweight than African-American males.

The results of the BMIs are provided to parents whose children are found to be overweight in the form of letters telling them their children's percentile status. Some parents were affronted by the letters, Rockenbach concedes, viewing them as criticism of their parenting. But the effects of the communications have become more apparent each year of the program, with increasing numbers of parents now appearing in the offices of pediatricians armed with the letters and asking what they need to do to help their children.

In cautions to states planning to implement body mass index assessments similar to Arkansas's, the federal Centers for Disease Control and Prevention (CDC) has pointed out that growth charts, including BMIs, are not intended to be used as the "sole diagnostic instrument" for measuring children's health. "Instead," the CDC says, "growth charts, including BMI-Index-for-age charts, are tools that contribute to forming an overall clinical impression of the child being measured."

The CDC also makes clear that any assessment of body mass index should keep in mind that what works for adults does not work for children. Because children's body fatness changes over the years as they grow, and because girls and boys differ in their body fatness as they mature, BMI for children is referred to as BMI-for-age and is plotted on gender-specific specific growth charts for children, with each chart containing a series of curved lines indicating specific "percentiles." Body mass index decreases during the preschool years and then increases into adulthood, and the percentiles show this pattern of growth, the CDC notes.

Editor's note: Recent converts to the BMI are schools in states with some type of student BMI reporting requirements currently in place (including, as of 2005, Arkansas, California, Florida, Illinois, Missouri, Pennsylvania, Tennessee, and West Virginia). An unknown number of school districts appear to have decided on their own to measure BMI as part of traditional height-and-weight assessments. All of this new interest means that a substantial percentage of children are now having body mass index percentiles added to their school health records.

Information about body mass index-for-age screening for students is available from the Centers for Disease Control and Prevention websites www.cdc.gov/growthcharts or www.cdc.gov/needphp/dnpa/growtycharts/bmi_tools.htm

See also: InFocus—Body Mass Index for Children, by the Center for Health and Health Care in Schools, at www.healthinschools.org, Childhood Overweight: What the Research Tells Us at www.healthinschools.org/sh/obesityfacts.asp and Co-Morbidities of Childhood Overweight, Health and Health Care in Schools at www.healthinschools.org/ejournal/2006/april2.htm.