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In 2003, Arkansas became the first state to send home BMI reports about all students as part of a broader anti-obesity initiative. But in the 20 years since, the state’s childhood obesity rates have risen to nearly 24% from 21%, reflecting a similar, albeit higher, trajectory than national rates. During the pandemic, the state obesity rate hit a high of more than 26%.

Still, at least 23 states followed Arkansas’ lead and required height and weight assessments of students. Some have since scaled back their efforts after parents raised concerns.

One school district in Wyoming used to include a child’s BMI score in report cards, a practice it has since stopped. Ohio allows districts to opt in, and last year just two of 611 school districts reported BMI information to the state. And Massachusetts stopped sending letters home. Even Arkansas changed its rules to allow parents to opt out.

Multiple studies have shown that these reports, or “fat letters” as they’re sometimes mockingly called, have had no effect on weight loss. And some nutritionists, psychologists, and parents have criticized the letters, saying they can lead to weight stigma and eating disorders.

BMI as a tool has come under scrutiny, too, because it does not consider differences across racial and ethnic groups, sex, gender, and age. In 2023, the American Medical Association called the BMI “imperfect” and suggested it be used alongside other tools such as visceral fat measurements, body composition, and genetic factors.