Should schoolchildren receive “fitness report cards” telling them whether their body mass index puts them in the overweight category for their age? The argument for fitness report cards is that, since a surprising number of parents aren’t aware that their overweight children are overweight, an informational intervention might help parents get their kids on a healthier path. The arguments against fitness report card are that they stigmatize children and scar their self-esteem, and that BMI is a poor indicator of overall health status (and, by the way, was never intended to be used as an diagnostic tool for individuals, although that horse is apparently out of the barn).
Until now, there’s been little evidence whether fitness report cards have a positive effect on children’s health or weight. But a new study of New York City public schools’ “Fitnessgrams” indicates that classifying girls as overweight doesn’t help them reduce their BMI—and might actually cause them to gain more weight.
The researchers—Douglas Almond and Ajin Lee of Columbia University and Amy Ellen Schwartz of NYU and Syracuse—analyzed 442,408 anonymized BMI records of New York City girls whose weight placed them just above and below the “overweight” cutoff for their age between 2007 and 2012.* They theorized that whether a borderline overweight girl fell above or below the cutoff was largely due to chance, because of “day-to-day variation in weight; diurnal variation in weight; measurement error in recorded height; differences in weight when measured across different scales, and students not knowing in advance when the in-school Fitnessgram BMI assessment will occur.”
They found that “being labeled as overweight has little and, if anything, a small positive effect on next year’s BMI … and next year’s weight.” Girls who were told they were overweight gained, on average, 0.17 pounds more than “healthy” girls, and their BMI increased by 0.03 BMI more units, over the course of the following year. For girls who were told they had a “healthy” weight one year and then told that they were “overweight” the following year, the impact was even more pronounced—their BMI subsequently increased 0.07 BMI units more than girls whose weight remained “healthy.” These finding line up with a previous study indicating that “Being labeled ‘too fat’ in childhood was associated with higher odds of having an obese BMI nearly a decade later.”
Because Almond, Lee, and Schwartz were using anonymized data, we have no way of knowing precisely why girls who were classified as “overweight” gained more weight than girls who were classified as “healthy”—but it’s not hard to guess. A school telling a student that she needs to lose weight seems only moderately more constructive than a drive-by street harasser yelling, “Hey, fatty.” Being labeled as fat might make girls feel hopeless about their weight and decide that there’s no point in exercising or eating healthfully, since they’re already “overweight.” On the other end of the spectrum, it might encourage girls to adopt restrictive diets that trigger weight cycling or so-called “yo-yo dieting,” or a more intractable problem like a binge-eating disorder. Even when it doesn’t have an affect on weight, telling impressionable children that there’s something wrong with their bodies is simply cruel and damaging. Consider the 66-pound nine-year-old whose story went viral in 2014 after her Fitnessgram told her she was fat. According to her mom, “She started jiggling her thighs, and saying, ‘Is this what they mean?’”
Schools can play an important role in teaching children about healthful habits: Gym classes (hopefully) teach children about the importance of exercise for psychological and physical health. Home economics can give adolescents the basic kitchen skills they need to cook healthy meals for themselves. All children, regardless of weight, can benefit from exercise and healthy eating, and schools are ideally situated to instill these healthy habits. Of course, serious investment in children’s wellbeing requires a lot more time and money than simply sending home a stigmatizing piece of paper with an arbitrary label on it—but it's also a lot less likely to backfire.
Correction, March 14, 2016: This post originally misstated that Amy Ellen Schwartz is academically affiliated with Columbia University. She’s academically affiliated with NYU and Syracuse.