Maximal Weight Loss Is Strongly Correlated With Maximal BMI in Adolescents With Anorexia Nervosa and Atypical...

In hospitalised patients with both anorexia nervosa (AN) and atypical AN, premorbid body mass index (BMI; kg/m²), estimated from premorbid weight (i.e., weight at the onset of weight loss preceding eating disorder development) and admission height, strongly predicts admission weight loss (i.e., premorbid weight minus admission weight). We hypothesised that maximal weight loss (i.e., maximal historical weight minus minimal weight since eating disorder onset) is also correlated with maximal BMI.

In 520 female adolescents with AN (n = 503) and atypical AN (n = 17), relationships between admission age, admission and maximal weight loss, and maximal and minimal BMI were analysed with non-parametric Spearman's correlation coefficients.

Like premorbid BMI in previous studies, maximal BMI was strongly correlated with maximal weight loss.

Maximal BMI appears to be a sound substitute for premorbid BMI in correlations with admission weight loss in hospitalised adolescents with AN and atypical AN. Consistent use of maximal (vs. premorbid) BMI and admission (vs. maximal) weight loss in research would align with the metric weight suppression (derived from both maximal and current weight), thus facilitating cross study comparisons. Additional studies should assess correlations between both premorbid and maximal BMI and admission or maximal weight loss to attempt to identify the variables with the highest predictive value.