Lack of sensitivity of weight targets compared with body cell mass for determining recovery from malnutrition in adolescents with anorexia nervosa

Objective: Using body weight targets to assess recovery from malnutrition in adolescents with anorexia nervosa (AN) may lead to premature discontinuation of refeeding programs. We examined body cell mass (BCM) to determine nutritional recovery, comparing with conventional indices based on weight. Method: Body mass index (BMI), Z-score, percentage of ideal body weight (IBW), and BCM (by total body potassium) were studied in adolescent females with AN (n = 92). Results: Fourteen percent had 'normal' weights (>85% of IBW), 24% had 'acceptable' BMI values (> 16), and 15% had 'acceptable' Z-score values (>-1) when their BCM was not fully restored. Discussion: The use of percentage of IBW, Z-scores, or BMI lacks sensitivity in determining adequacy of nutritional rehabilitation. Body compartmental analysis particularly of BCM and body fat is recommended, and the use of BMI particularly should be discarded.