A study reveals changes in eating habits occur months before parents notice

Adolescent girls who develop anorexia typically engage in unnoticed dieting for up to six months before an official diagnosis is made, according to a study coauthored by a Rutgers researcher.

“Dieting is a well-known precursor behavior to more serious restrictive eating behaviors,” said Lauren Davis, a doctoral student in the Rutgers Department of Psychology and coauthor of the study, published in the Journal of Adolescent Health. “Our work expands on this knowledge and describes when girls start dieting, how this can happen without anyone else in their life knowing, and how dangerous the habit can be.” 

While anorexia commonly begins in adolescence, how and when symptoms emerge and evolve hasn’t been well documented. Davis, working with colleagues from Columbia University Irving Medical Center, surveyed 64 adolescent girls ages 12 to 18 who were receiving treatment at the New York State Psychiatric Institute. Participants were asked about dieting, restriction, binge eating, purging, excessive and compulsive exercise, weight history and amenorrhea.

Body mass index percentiles were calculated, and adolescents completed the Eating Disorder Examination-Questionnaire, which is used to assess eating disorder behaviors and attitudes. At least one parent of each girl was interviewed.

Researchers found that dieting was typically the first symptom to emerge, slightly before age 14 as reported by the child, and slightly older than 14 as reported by the parent. Most of the behaviors tended to emerge between 14 and 14.5 years of age, with the average age of formal anorexia diagnosis being made at slightly more than 15 years.

The order of symptom emergence was identical for child and parent: dieting, restriction, being underweight and excessive exercise. What differed was the timing; children reported dieting about six months earlier than their parents noticed.

“While this requires further research, these findings suggest that teenagers may hide their eating behaviors,” Davis said. “Adolescents are at school most of the day, and they could be cutting down on their eating or trying to change patterns of eating outside the view of their parents.”

Davis said she hopes this work will help caregivers in the identification and early intervention of eating disorders like anorexia. Overt signs of a problem include skipping meals or openly talking negatively about shape or weight. More covert warning signs of anorexia nervosa include fluctuating weight or weight loss; obsession with calories and dieting; rigid, inflexible thinking about food or mealtimes; wearing baggy clothes to hide body shape; and exercising more frequently or intensely than usual.

More research needs to be done to understand the timeline between dieting and anorexia, Davis said.

“We live in a fat-phobic, weight-focused society,” she said. “Adolescents reporting engaging in dieting prior to when their parents notice is something that doctors, parents, schoolteachers or anyone in a young girl’s life should be aware of. While not every adolescent who starts dieting is going to develop an eating disorder, dieting is one of the best-known precursor behaviors to developing one.”

A researcher from New York State Psychiatric Institute led the study. Researchers from Columbia University Irving Medical Center and Duke University School of Medicine also contributed to the research.