"She goes, 'Does this mean I'm fat?' and I said, 'No, this does not mean you are fat,'" Amanda Moss, of Belton, Missouri, told KMBC, ABC's Kansas City affiliate.
Moss's daughter Kylee is 7 years old, 54 pounds, 3-foot-10, Moss told the station.
"She is tiny," Moss told KMBC. "She has no body fat at all."
The school calculated students body mass indexes, which are a measurement of height, weight and age, as part of a grant program, Belton School District Superintendent Andrew Underwood told ABC News. In the future, he said parents will be allowed to opt out.
"We do the body mass index on our students for positive reasons to try to promote healthy habits as far as what the kids eat and their activity," Underwood said. "There was no malicious intent by this."
"[I]t may in fact be psychological[ly punishing, since school personnel may not be familiar with details regarding that child's health," he said in an email to ABC News. "This is best addressed by that child's healthcare provider. That being said, if the school is in a neighborhood with limited access to healthcare, the child might not be seeing a pediatrician regularly. In that scenario, the school report to the child's parents on BMI might be a much needed wake-up call."