{"p"=>{"__content__"=>"The methodology of characterizing weight and measuring weight change in adolescents with anorexia nervosa (AN) and atypical AN is variable, limiting the cross-comparability of research studies. We aimed to compare correlations between absolute weight, weight loss, and weight gain during and following inpatient treatment in a combined sample of 110 medically hospitalized adolescents with AN ( = 33) and atypical AN ( = 77) and the two diagnostic subgroups. We hypothesized stronger correlations in the combined sample versus diagnostic subgroups. Body weights (premorbid, admission, discharge, 3-, 6-, and 12-month follow-ups) were characterized by body mass index (BMI), BMI z-score (BMIz), and percent median BMI scores (%mBMI). Weight loss and gain were measured via difference scores (Δ) in kg, BMI, BMIz, and %mBMI. Non-parametric Spearman’s correlations determined correlation coefficients between absolute weight characteristics and weight change metrics. Generally, correlations for weight characteristics between any two follow-ups were highest in the combined sample and highly similar, regardless of characterization. Correlations between premorbid weight characteristics and weight loss metrics were strong and very strong in the combined sample and subgroups, respectively. In the combined sample only, admission weight characteristics were strongly correlated with weight gain in ΔBMIz at all follow-ups; correlations using the other weight gain metrics were moderate. We conclude that our overarching hypothesis was largely confirmed. Partially sizeable differences in correlations, particularly in comparisons within the AN subgroup, warrant consideration. Weight gain metrics cannot be used interchangeably. Upon confirmation in independent samples, our findings tentatively guide the selection of weight characteristics and metrics yielding the strongest correlations in adolescent samples. Findings are discussed in the context of a homogeneous conceptualization of AN and atypical AN.", "i"=>[{"__content__"=>"n"}, {"__content__"=>"n"}]}}