Young women who develop anorexia nervosa exhibit a persistently low premorbid body weight on average: A longitudinal investigation of an important etiologic clue.

OBJECTIVE

test whether (1) young women who subsequently show onset of anorexia nervosa (AN) exhibit persistently lower average premorbid BMI than those who subsequently show onset of bulimia nervosa (BN), binge eating disorder (BED), purging disorder (PD), or no eating disorder; (2) a proximal spike in other risk factors occurs immediately before AN emergence; and (3) psychological and behavioral factors differentiate youth who show persistently low BMI from those who do not.

METHOD

Data from a sample ( = 1952) of young women at high-risk for eating disorders followed for 3 years and a socioethno-racially representative sample ( = 496) of adolescent girls followed for 8 years were used to address these aims.

RESULTS

Participants who developed AN exhibited significantly lower average measured premorbid BMI over repeated assessments than those who showed onset of other or no eating disorders. Dietary restraint, negative affect, and eating affect regulation expectancies significantly increased immediately before AN onset. Youth who showed persistently low BMI reported lower pressure for thinness, body dissatisfaction, and dieting at baseline, implying that elevations in these factors did not drive the low BMI.

CONCLUSIONS

The evidence that young women who subsequently show AN onset exhibit a low premorbid BMI on average is novel and suggests that etiologic models should incorporate this finding and selective prevention programs should target low-BMI adolescent girls. The finding that dieting, negative affect, affect-regulation eating expectances spiked immediately before emergence of AN is also novel and suggests that it might be useful for selective prevention programs to target these factors. (PsycInfo Database Record (c) 2022 APA, all rights reserved).