3 - (SYM 132) Is There a Basis for a Weight Cut-off Point? A Large-scale Investigation of Atypical Anorexia and Anorexia Nervosa Subtypes in a Residential Treatment Sample

Background: There is much debate surrounding how to differentiate between anorexia nervosa (AN) and atypical AN (AAN) as diagnostic entities, and whether a distinction based on BMI is warranted in our current diagnostic system. Severity of illness has historically been equated with low weight, but research has not examined how BMI interfaces with psychopathology. Better understanding eating disorder and emotional symptomatology across AAN and specific AN subtypes (i.e., AN-restricting, AN-binge/purge), with and without controlling for BMI, can inform how AAN may differ from other AN subtypes and whether there is a basis for a weight cut-off point.

Methods: Participants were 1810 female patients at a residential eating disorder treatment center who completed surveys at intake. One-way analysis of covariance (ANCOVA) tests assessed differences between individuals with AN-restricting subtype (AN-R; n = 769), AN-binge purge subtype (AN-BP; n = 650), and AAN (n = 225) on measures of eating disorder cognitions, depressive and anxiety symptoms, anxiety sensitivity, experiential avoidance, and mindfulness, with and without controlling for BMI.

Results: Individuals with AAN reported the highest BMI, followed by AN-BP, then AN-R. Relative to AN-R, AAN and AN-BP groups endorsed significantly higher symptomatology on measures of eating disorder symptoms, anxiety sensitivity, depressive symptoms, experiential avoidance, and significantly lower mindfulness (all p < .001), but AAN and AN-BP groups did not differ from one another. When controlling for BMI, differences between AAN and AN-R did not remain significant.

 
Conclusion: Our results finding more severe eating disorder and emotional symptoms in AAN compared to AN-R suggest that it may be problematic to rely on BMI as a proxy marker of illness. Rather, the higher BMI of individuals with AAN appears to account for heightened eating disorder and emotional symptoms in this group. Heightened psychopathology may be attributed to the reality of living in a higher weight body in a fatphobic society that stigmatizes individuals of higher weights. It may be important to remove the weight criterion altogether for diagnosing AN, in order to reduce disparities in treatment and increase recognition of restrictive eating disorders across the weight spectrum.