Among Lexie Manion’s memories of her junior year of high school in New Jersey was the experience of being regularly hassled by a school nurse who was trying to weigh her.
The nurse, Manion recalled, was trying to get Manion’s weight on file — a common practice at schools across the United States, which aim to use the data to improve student health. But for Manion, who had an eating disorder, the experience was deeply distressing. The thought of getting on a scale in school — of someone other than her doctor handling this sensitive measurement — terrified Manion. It also triggered her eating disorder: She began to restrict her food intake more intensely to lose weight before the school nurse put her on a scale.
“I was worried about her knowing my weight and I was worried the whole school would somehow know the number if she weighed me,” Manion, now 29, wrote in an email to Undark. “I became very anxious and would avoid the scale and her gaze every time she inquired.”
The policy at Manion’s school was part of a national effort to combat childhood obesity by collecting — and often sharing — data on students’ weight. Starting in 2003, one study found, 29 states enacted policies encouraging or requiring school districts to weigh students, or to go further and screen their students for body-mass index, or BMI, a common tool for categorizing a person’s weight. By the policy’s peak extent, in the 2010s, millions of students each year were receiving so-called “BMI report cards” in the mail — and some students even saw their weight status appear on actual report cards, alongside their grades. Policymakers hoped that by telling students and their families about a child’s weight category, the reports would prompt them to make healthier choices and lose weight, reducing childhood obesity one student at a time.
But even as the practice was becoming more common, research was already suggesting that BMI screenings have no impact on students’ weight and can even cause harm. Today, many experts say, the evidence is clear that school BMI screenings do little to improve student health. Research has also linked the policy to higher rates of body image dissatisfaction, increases in weight-based bullying and, as in Manion’s experience, triggering or worsening eating disorders. In response, some states, including California, have stopped requiring screenings.
“I was worried about her knowing my weight and I was worried the whole school would somehow know the number if she weighed me”
Nevertheless, BMI screening or similar policies that mandate or encourage weight-tracking remain on the books in at least 16 states, according to Undark’s review of state legislative codes. Among them are Tennessee, West Virginia, Arkansas, and New York.
“To focus efforts on just measuring the increasing waistline of America is a Band-Aid,” said Kristine Madsen, a pediatrician and public health nutrition researcher at the University of California, Berkeley, who conducted one of the largest studies of school BMI screenings to date. “It doesn’t even touch the underlying problem, and it’s ineffective.”
Arkansas was the first state in the nation to mandate screening and reporting, back in 2003. Then, in 2005, the Institute of Medicine at the National Academy of Sciences, or NAS, released a 434-page report, “Preventing Childhood Obesity: Health in the Balance,” that urged more states to adopt the practice. “It is important for parents to have information about their child’s BMI and other weight-status and physical fitness measures, just as they need information about other health or academic matters,” the NAS group wrote.
The group was responding to what they described as a childhood-obesity epidemic. At the time, around one-third of U.S. children were classed as overweight, obese, or severely obese. Childhood obesity is linked to a range of poor health outcomes, including high blood pressure, asthma, and heart disease.
More states moved to implement BMI screening. By 2010, just five years after the NAS’s recommendation was published, 29 states were widely conducting some form of body assessment on their students, according to an academic survey of state education departments.
By the policy’s peak extent, in the 2010s, millions of students each year were receiving so-called “BMI report cards” in the mail — and sometimes on actual report cards, alongside their grades.
Those policies typically offered little guidance on how the weigh-ins should be conducted. According to one study, about half of screenings were done during gym class, often in front of other students. The gym teacher or school nurse would measure each student’s height and weight and submit them to the school, which, in many cases, would pass the data along to state health authorities for population-level tracking.
Baked into that model from the start, some experts say, were problems. Foremost among them was the reliance on BMI in many policies.
The metric, first proposed in 1832, was popularized after research in the 1970s, which only involved men and was not representative of the ethnic and racial diversity of the United States, supported its use. BMI also doesn’t consider factors like muscle mass. “This was intended to describe large groups of people; it was not intended to be an individual litmus test for health,” said Leah Graves, a registered dietitian who specializes in treating eating disorders. Graves and others question whether BMI necessarily offers families useful information about students’ overall health.
The policies soon ran into another problem: There wasn’t much evidence that they worked.
Not long after the NAS recommendation was released, scientists began publishing studies on school weigh-ins. In 2009, for instance, two pediatrics experts published a review of the existing research, finding that there was no impact on students’ weight. Parents, they wrote, didn’t seem to be learning much from BMI report cards, and there didn’t seem to be any increase in healthy behaviors at home.
In 2014, Madsen, the Berkeley researcher, and several colleagues launched a randomized clinical trial. The researchers took nearly 29,000 students in California public elementary and middle schools and split them into three groups. One group didn’t get screened at all. The second was screened, but they never found out the results. A third group received screenings, and their caregivers were sent BMI report cards. The researchers followed the group from 2014 to 2017 to track changes in weight and adverse outcomes.
The team’s results, published in 2021, showed that neither the screening nor reporting had an impact on weight change over the years. Additionally, the two groups that were screened reported more weight dissatisfaction and peer weight talk than the group with no screenings.
Madsen’s research has also found that the experience can be upsetting for students. In one 2022 survey of more than 11,000 students in California, her team found that 49 percent were weighed by gym teachers, as opposed to just 28 percent who were weighed by school nurses; the students were more likely to feel less comfortable being weighed by a teacher than a nurse, and that they felt they lacked privacy while being weighed.
Other research has documented the potential for long-term harms from that experience. The negative effects of adolescents perceiving themselves as overweight can last for years into adulthood, long after the screenings have ended, according to one 2023 survey. While the study didn’t specifically ask about BMI screening, it linked perceived overweight status to increased self-starvation, binging, purging, and overexercising, as well as the development of eating disorders.
Not every expert is convinced that BMI screening for the sake of data collection is necessarily harmful. Researchers and school professionals say it’s the way these screenings are conducted that can cause problems. As a result, some professional organizations and government agencies have issued guidelines intended to improve the experience.
The Centers for Disease Control and Prevention, which has no formal position on BMI screenings, has a public set of 10 safeguards schools can implement to address concerns about screenings. The list includes recommendations like measuring students’ height and weight in a private place, having nurses take the measurements instead of teachers, and asking for parental consent before measuring students.
But a 2019 CDC survey of more than 200 schools found that its safeguards had not been widely implemented. Only 3 percent of the schools had at least four of the safeguards in place, and 19 percent had no safeguards at all.
The two groups that were screened reported more weight dissatisfaction and peer weight talk than the group with no screenings.
“These safeguards came out kind of pragmatically, recognizing that there’s not enough evidence at that point to say whether or not BMI measuring schools is definitively harmful or helpful, but schools are doing it,” said CDC school health researcher Sarah Sliwa. “So, if they’re doing it, what are some steps they can take to try to minimize those harms and increase the likelihood that data are collected in a way that’s transparent and useful?”
As the school staff members who are most often asked to weigh students, physical educators also have developed standards regarding body measurement in schools.
The Society of Health and Physical Educators, or SHAPE America, a professional organization, has a formal statement on fitness testing — which can include BMI screenings among other assessments — that states the organization finds the testing valuable only when integrated appropriately into the curriculum, and when the results aren’t used to grade students. SHAPE America recommends that schools first teach students about the fitness testing and why it’s done, as well as prepare them for the process and set personalized goals based on the outcome of the testing. But the organization does not have an official recommendation on whether to conduct BMI screenings.
Support Undark Magazine
Undark is a non-profit, editorially independent magazine covering the complicated and often fractious intersection of science and society. If you would like to help support our journalism, please consider making a donation. All proceeds go directly to Undark’s editorial fund.
“There’s a lot of body stigma, and we have other data points that we can use without having students feel that they’re being judged,” said SHAPE America president Cara Grant.
The American School Health Association, an organization of school nurses and other health professionals, also does not have an official position on BMI screenings, said former president Kayce Solari Williams.
In order to effectively realize the CDC guidelines, Sliwa said, schools need to implement safeguards or best practices. Because of a lack of the funding and staffing, though, they often fail to do so.
Some states have responded to the research showing harms from BMI screenings. In 2013, Massachusetts struck BMI reporting from its schools, but maintained a screening requirement. Illinois made BMI screening optional for its students in 2015. California eliminated screening and reporting requirements from its annual fitness testing. In New York, schools still screen for BMI, but they are no longer required to send BMI report cards home.
Other states have not made changes. In Georgia, screening and reporting are required by law. West Virginia, which has some of the highest levels of childhood obesity in the country, state law requires the collection of BMI data to be reported to the Department of Education, the governor, the state Board of Education, the Healthy Lifestyles Coalition, and the Legislative Oversight Commission on Health and Human Resources Accountability.
“There’s a lot of body stigma, and we have other data points that we can use without having students feel that they’re being judged.”
In New Jersey, where Manion attended high school, BMI screening is not mandated, but it’s allowed on a district-by-district basis. The state does require weight measurement, however.
“What’s the value?” asked Madsen, the Berkeley researcher. She questions whether the policies are a good use of school resources. “The entire point of sending them home is actually to support families and in creating healthier lifestyles,” she said. “But they’re not.”
Amanda Salazar is a freelance journalist from Brooklyn, New York, covering science and politics. She’s written for over 15 publications and has a master’s in science reporting.
