BMI Letters: Shameful or Useful Tool?

11/22/2013

youth sports weight bmi
Photo by massdistraction / CC BY-NC-ND

Did you hear about the lady in North Dakota who, instead of handing out treats to visiting Halloweeners, gave out a letter letting their parents know she believed they were overweight and shouldn't be receiving candy?
 
This isn't the first use of a letter to inform parents of their child's weight status. Schools have been using the BMI and what many refer to as "fat letters" for years.
 
BMI stands for Body Mass Index. If you're unfamiliar with the term, it is the current terminology for evaluating the health, growth and weight status of children (and adults). It is an indicator of body mass and is often used as a tool reflecting normal growth, overweight and underweight.
 
Several schools across the country use the BMI to screen children for overweight, obesity and overall health. But what exactly does BMI look at? BMI is an equation whereby body weight and height are factored to assess the appropriateness of weight status for the actual height of an individual. A high BMI value may indicate overweight (>85%ile) or obesity (>95%ile). A BMI that falls between the 5-85%ile is considered "normal," while the BMI values that fall below the 5%ile are evaluated as underweight.
 
Although not proven to reverse or even have a positive impact on obesity, many believe using BMI as a tool in schools and their associated informational letters are needed, as some parents are unaware of their child's weight and the dangers it may pose to overall health. Yet, others believe that these BMI letters are 'fat-shaming,' potentially having a lifelong negative impact on children and teens.
 
For the growing athlete, BMI measurements can pose a challenge. Since BMI reflects total body mass, which is made up of muscle, fat and bone, BMI values may be skewed, particularly in the muscular athlete. Also, studies indicate that some children have heavier bones or are "big-boned" which may also skew the BMI to a higher value. For example, the high school football player may classify as "overweight" or "obese" with the BMI tool, yet have a low body fat content, increased muscularity and be quite healthy.
 
As a mom and dietitian, I know the most important indicator of growth and development is what has happened over time. Has growth been steady, following a predictable pattern on the growth chart, or has there been a dramatic increase or decrease in weight?
 
Unfortunately, BMI screening in schools and "fat letters" often fail to include this long-term information, leading to a measurement tool that reflects only one point in time.
 
What is concerning is how parents may react to these well-intentioned letters, such as putting kids on weight loss diets, or ignoring or not understanding the information about BMI, particularly if they find it offensive. Neither scenario works on behalf of the child. If in fact a child is overweight or obese, it doesn't help to ignore it, because it isn't likely to get better on its own. A healthy diet, exercise and addressing problematic eating behaviors will need to be addressed.
 
Alternatively, placing children on weight loss diets is never indicated without medical supervision and can interfere with normal growth, nutrient adequacy and self-esteem development, not to mention athletic performance. Diets are also linked to the development of eating disorders.
 
How do you feel about the BMI measurement tool or 'fat letters,' especially for athletes? Sound off in the comments below!

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