How to define anorectic weight?

• Published in: European eating disorders review Vol. 7; no. 5; pp. 321 - 333
• Main Authors: Oehlschlägel-Akiyoshi, Jens, Malewski, Peter, Mahon, Jennifer
• Format: Journal Article
• Language: English
• Published: Chichester, UK John Wiley & Sons, Ltd 01.11.1999
• Subjects: Benn's index; body mass index; diagnosis of anorexia nervosa; DSM; ICD; intra-individual criteria; LMS-method; median BMI; relative weight; robust estimation; underweight; weight-for-height index
• ISSN: 1072-4133; 1099-0968
• DOI: 10.1002/(SICI)1099-0968(199911)7:5<321::AID-ERV313>3.0.CO;2-L

Different definitions of weight criteria for the diagnosis of anorexia nervosa have been introduced, and all of them are problematic. For example, ICD‐10 (World Health Organization, 1992) suggests using 17.5 BMI instead of 85 per cent expected weight. It is shown that any weight‐for‐height indices (including BMI) are inadequate corrections for body size. Furthermore BMI is not an optimum weight‐for‐height index, but is rather an approximation of relative weight. Data from several countries indicate that the proportion of the population with weight below 17.5 BMI depends on age, sex and race. We suggest returning to Benn's definition of relative weight. It gives a clinically meaningful intra‐individual scale, on which patients may be compared across populations. We show that BMI may be used to calculate relative weight and suggest a diagnostic criterion of 85 per cent of median BMI from sex‐, age‐ and country‐specific tables. Such tables are already provided for German, English, French, Swedish, Italian, Japanese and (white) US populations. Copyright © 1999 John Wiley & Sons, Ltd and Eating Disorders Association.