Down the hall from the cafeteria and away from the gym, schools are deploying one of the latest weapons in the fight against childhood obesity - mandated measurements of body mass index.
On a recent afternoon, seventh graders at Robert K. Shafer Middle School in Bensalem waited as school nurse Kathleen McLaughlin recorded their heights and weights, the first step in tabulating BMIs. Each child's score, an indicator of body fat, will be mailed home in letters some have dubbed "obesity report cards."
Concern over childhood corpulence has led at least a half-dozen states to require in-school BMI calculations, intended to alert parents of a present or looming weight problem.
Pennsylvania expanded screenings to grades five through eight this year after launching the program in all elementary schools in the 2005-06 academic year. In New Jersey, where legislation is being considered, some schools have begun efforts of their own.
Locally, administrators report few complaints about the screenings. But those involved with BMI tests say they step carefully around emotional land mines - and not just with kids.
Adolescents "are more aware of body image," McLaughlin said. "You have to be careful how you're talking to them."
At Shafer, she inquired about activities and snacks, no judgments made. And she pushed fruits, vegetables and calorie-burning extracurriculars.
Wendy Wilkinson of Pottstown dismissed her 6-year-old daughter's BMI report, which placed her in the 99th percentile, indicating overweight. It's "really silly," she said. "She is chubby now, but she goes into growth spurts."
Marcia Shinn of Pitman also was upset that her 11-year-old girl, who plays football, was found at risk for being overweight. "They just measured based on her weight and height and not physical activity," Shinn said. "It infuriated me."
Some parents and experts are concerned that so much talk of BMI - and students do compare, say nurses - may distort a child's body image, especially among older girls at risk for anorexia and bulimia. In addition, perceptions of heaviness vary by racial and ethnic groups.
"You're going to put another label on a kid," said Wendy Cramer of the Renfrew Center, a Philadelphia treatment facility for eating disorders. "I definitely worry about what's going to happen when this gets to high school." In Pennsylvania, that will be this fall.
Arkansas lawmakers, who passed the nation's first BMI bill in 2003, curtailed the screenings this year because of parent complaints. Testing is now every other year; 11th and 12th graders are exempt, and parents can opt not to have their children participate.
The laws stem from a huge increase nationally in the number of overweight youths - four times more than 40 years ago - and concern for their future health. Groups such as the Robert Wood Johnson Foundation, which last week announced plans to spend $500 million on programs to give children more exercise opportunities and affordable, healthy food, hope to reduce the number of kids whose obesity puts them at risk for adult diseases.
In a 2003 pilot program, BMI screenings at 10 Pennsylvania schools - including the Erdenheim-Enfield elementary schools in Springfield Township, Montgomery County - found 38 percent of students were overweight or at risk.
Children in the 95th percentile or higher are considered overweight. (Experts do not use the adult term "obese.") Those between the 85th and 95th percentiles are at risk for being overweight, while those below the fifth percentile are underweight.
Districts consider the BMI letter home an aid to parents, who are encouraged to consult their child's doctor.
The idea is "to detect health issues early," said Allison Topper, head of Pennsylvania Advocates for Nutrition and Activity, which worked with the state on educational materials.
"It is a screening," she emphasized, "not a diagnostic tool."
For grade-schoolers, the yearly evaluations are more fun than anything, said nurse Kim Glielmi of Hillcrest Elementary School in Drexel Hill, where a BioMeasure machine records weight and height in seconds.
"Kids wouldn't know 99 is bad," she said. Adults, however, "are sensitive." A high score can feel like an indictment of their parenting skills.
"There's such a close relation between nurturing and nourishing," said nutritionist Eileen Ford of Temple University's Center for Obesity Research and Education, who supports the screening program for assessing health risks.
Michelle DeCarlo's 8-year-old daughter, Julianne, a soccer and lacrosse player, had a BMI score at the upper end of the normal range. DeCarlo was reluctant to share it with her.
"With young girls, it's such a sensitive subject," she said. "You don't want to focus on image and what they look like."
Experts caution that BMI numbers aren't foolproof tests. A child's height and weight may change dramatically from year to year, and athletes can score high because of muscle mass.
"It's really intended to be a measure for adults and morbid obesity," said Kim A. Logio, an assistant professor of sociology at St. Joseph's University who studies body image.
The Lower Merion School District met the new state guidelines with care and caution. Weight is "the big taboo," said Terry Quinlan-Clampffer, coordinator of health services. Even young students talk of diets.
A BMI committee organized parent sessions to stress the importance of focusing on the total picture. Health classes addressed body image, and reports sent home noted the test's limitations. Student privacy was guarded by using no parent volunteers at measurements.
"We've seen little anxiety with the kids," Quinlan-Clampffer said. "I can't think of any complaints from parents at all. That's amazing."
About 21 percent of Lower Merion elementary students scored at risk of becoming overweight or worse this year, she said. For middle schoolers, the number was 26 percent.
Though the figures were lower than average, Quinlan-Clampffer was still surprised. "It shows you get used to seeing overweight," she said.
At Shafer, nurse McLaughlin counseled a self-conscious student that adolescence can be a time of weight gain and encouraged him to join an after-school activity. He passed on swimming and karate, but considered the walking club.
At 13, Dominique Thompson, who is almost 5-foot-1 and 120 pounds, plays field hockey and devours green beans and grapes. She was surprised to find her BMI just over the at-risk line. Most middle school girls, she said, "talk about being on diets." She would like to shed a couple of pounds, but plans to turn to exercise.
That's the goal, said McLaughlin - to focus not on weight, but "on kids making better choices."
To calculate your child's body mass index, and to learn more about fighting childhood obesity, go to http://go.philly.com/bmiEndText