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“Observing children whose BMI trajectories persistently and significantly deviate from age norms for signs and symptoms of ED [eating disorder] could assist in identification of high-risk individuals,” wrote Zeynep Yilmaz, Ph.D., of the University of North Carolina at Chapel Hill and colleagues.
The researchers analyzed a subset of data from the Avon Longitudinal Study of Parents and Children (ALSPAC), which included 1,502 children who had at least one BMI measurement between birth and age 12.5 years. The ALSPAC determined BMI by collecting information about the participants’ height and weight via questionnaires sent to mothers on average every year and via face-to-face assessments with the participants every two years. The participants were assessed for eating disorders at ages 14, 16, and 18 years. The researchers then compared the average BMI over time of participants who had not developed an eating disorder with that of participants who had developed anorexia nervosa, bulimia nervosa, binge-eating disorder, or purge disorder.
Boys who later developed anorexia nervosa had significantly lower BMIs than those with no eating disorder by age 7. Girls who later developed anorexia nervosa had significantly lower BMIs than their peers with no eating disorders by age 3. Boys who later developed binge-eating disorder or purge disorder had higher BMIs than their peers with no eating disorders starting at age 9.5. (The occurrence of bulimia nervosa in boys was too low for the researchers to make a solid comparison between groups.) Girls who later developed binge-eating disorder had higher BMIs than their peers with no eating disorders starting at age 7, and girls who later developed bulimia nervosa or purge disorder began to have higher BMIs than their peers with no eating disorders at age 9.
The researchers emphasized the potential link between low BMI and anorexia nervosa.
“In [anorexia nervosa], premorbid low weight may represent a key biological risk factor or early manifestation of an emerging disease process,” they wrote.
For related information, see the Handbook of Assessment and Treatment of Eating Disorders by APA Publishing.
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