Experts say that an exact determination of expected body weight for adolescents based on age, height and gender is critical for diagnosis and management of eating disorders such as anorexia and bulimia.
A new study published in the journal Pediatrics compares three common methods for calculating expected body weight of adolescents with eating disorders and found that the body mass index (BMI) percentile method is recommended for clinical and research purposes.
Body mass index is defined as the individual’s body weight divided by the square of his or her height. The method was developed in the 19th century to guide population health studies.
“There are no clear guidelines in the adolescent field,” said study author Daniel Le Grange, Ph.D., professor of psychiatry and director of the Eating Disorders Program at the University of Chicago.
“We set out to do something that is relatively straightforward that hasn’t been done before, and that is look at some of the most frequently used methods of calculating weight in the pediatric and adolescent eating disorder populations, and see whether we can come up with a gold standard for clinical as well as for research purposes.”
Le Grange and his colleagues analyzed data from adolescents seeking treatment for eating disorders at the University of Chicago. They calculated expected body weights using the BMI method along with two other commonly used measures: the McClaren and Moore methods.
The BMI method compares a patient’s current BMI to the 50th percentile BMI for a patient of the same age, height and gender according to charts published by the Centers for Disease Control and Prevention. That percentage can help determine whether a patient has an eating disorder.
Their analysis showed that of the three, the BMI method was the most useful for children and adolescents of all ages, heights and weights, and could account more accurately for very short and very tall patients as well.
Health reform calls for primary care physicians to take a lead role in managing the overall health of their patients. This means that many family practice and pediatric providers, who may not be as familiar with eating disorders and prevalence of eating disorders, must provide appropriate care management for children with eating disorders.
“Pediatricians are at the forefront of making these diagnoses,” said Le Grange. “We wanted to make a clear statement to the pediatric and adolescent eating disorder community that we should all talk the same language and move forward in this way.”
The study also recommends that researchers cite the method used to calculate expected body weight in their research and stresses the importance of using the term “expected” instead of “ideal” to describe body weight to avoid unrealistic body image expectations in patients with eating disorders.
“I think it’s a good clear clinical guide, and I hope pediatricians in the community feel they can pick it up and have a handy tool in their clinical practice,” Le Grange said.