Seasonal and subtype differences in body mass index at admission in inpatients with anorexia nervosa.

Individuals with restrictive type AN show seasonal variations in body weight that are opposite to seasonal variations in body weight in individuals without AN. These seasonal effects are specific to the restrictive subtype and cannot be found for the binge/purge or atypical subtypes. Future studies that replicate this effect in other cultures or latitudes and that examine the mediating mechanisms are needed.