Could there be a way to tell years in advance which girls are more likely to develop eating disorders?
New research from Denmark suggests that childhood body mass index (BMI) may offer important clues. BMI is an estimate of body fat based on height and weight.
The new research linked lower BMI as early as age 7 with a higher risk of anorexia, an eating disorder in which people severely restrict calorie intake.
It also found an association between higher BMI and being overweight with an increased risk of bulimia, a binge-eating disorder in which episodes of extreme eating are followed by forced vomiting or fasting.
"There are many factors that influence the development of eating disorders," said lead author Dr. Britt Wang Jensen, of Bispebjerg and Frederiksberg Hospital in Copenhagen. "We find that BMI is an indicator of risk for anorexia and bulimia -- it is unlikely that it causes it."
The study examined records of over 66,500 girls, born between 1960 and 1996, whose height and weight were measured during annual school physicals from age 7 to 13. That information was paired with diagnoses of anorexia and bulimia found in Danish national patient registries.
The researchers tracked the girls from age 10 to 50.
Over that time, 514 women were diagnosed with anorexia at an average age of 20. Meanwhile, 315 were diagnosed with bulimia at an average age of 23.
The study authors said that their analyses revealed that as BMI increased, the risk of anorexia fell.
For instance, in two 7-year-old girls with a difference in BMI equivalent to just over 5 pounds, the girl with the higher BMI had a 14% lower risk of developing anorexia. This changed to 28% by age 13.
But, for this same BMI difference, the heavier girl had a 50% greater risk of bulimia in later life than the leaner girl. By age 13, the risk was 33% higher.
In other words, the girl who is 5 pounds heavier has a lower risk of anorexia and a higher risk of bulimia, Jensen explained.
Compared to 7-year-olds whose weight was in a normal range, those who were overweight had double the risk of developing bulimia later in life. The risk continued but at a lower rate by age 13, the findings showed.
"Our study shows that BMI may be an early indicator of the risk of developing eating disorders later in life and thus may contribute to tools that enable an earlier identification of girls at risk," Jensen said.
More study is needed to tease out the reasons.
The report was scheduled for presentation at an online meeting of the European Congress on Obesity, May 10 to 13. Findings presented at medical meetings should be considered preliminary until published in a peer-reviewed journal.
The researchers noted that the diagnoses found in the study may be more severe cases because they were based on hospital admissions and contacts.
Dr. Ellen Rome, head of the Center for Adolescent Medicine at the Cleveland Clinic Children's Hospital in Ohio, reviewed the findings.
Rome noted that the coronavirus pandemic has affected eating disorders in both predictable and atypical ways.
Predictably, pediatricians are seeing high numbers of kids with excessive weight gain who have binge-eating disorder. They are also seeing many normal weight, overweight or obese adolescents who have atypical anorexia, she said. The medical complications can be just as life-threatening.
Rome pointed out that people will cheer on an overweight kid who loses weight even if they're doing so in as dangerous a way as a severely underweight kid with anorexia.
"Disordered eating behavior in the face of weight loss in someone who is overweight is still invisible, and I'm not sure with this methodology whether this study could address any of that," Rome said.
She said "weighty" talk can fuel both eating problems and lower self-esteem in both girls and boys.
It's important to talk more about health and wellness than weight, she added. Instead of criticizing a child's weight, Rome said a doctor might say, "This year we're going to let you get taller and focus on learning how to eat really well."
Parents can pick up on that theme by explaining that healthy eating differs by age, because adults have different energy and nutrition needs than kids do.
"You don't teach calculus to a 5-year-old -- you teach simple math and then you adapt it as they grow," Rome said. "In the same way, we're going to teach healthy eating in different ways along that developmental spectrum."
The National Eating Disorders Association can be reached in a crisis by texting "NEDA" to 741741. Visit NEDA's website to learn more about eating disorders.
SOURCES: Britt Wang Jensen, PhD, researcher, Center for Clinical Research and Disease Prevention, Bispebjerg and Frederiksberg Hospital, Copenhagen, Denmark; Ellen Rome, MD, MPH, head, adolescent medicine, Cleveland Clinic, and professor, pediatrics, Cleveland Clinic Lerner College of Medicine of Case Western Reserve University, Ohio; European Congress on Obesity, virtual meeting, May 10 to 13, 2021