Changes in bioimpedance analysis after stable refeeding of undernourished anorexic patients

OBJECTIVE: To evaluate bioimpedance analysis (BIA) parameters in patients w ith anorexia nervosa when undernourished and then after stable refeeding. DESIGN: Follow-up study. SUBJECTS: Thirteen patients with anorexia nervosa who were studied when und ernourished (body weight (Wt): 36.9+/-5.6kg, body mass index (BMI): 14.8+/- 1.8kg/m(2)) and after stable refeeding (Wt: 52.9+/-7.1kg, BMI: 21.2 +/- 2.3 kg/m(2)) compared to 25 well-nourished control women (Wt: 53.7 +/- 4.9 kg, BMI: 21.1 +/- 1.3 kg/m(2)). MEASUREMENTS: Impedance and phase angle were determined for the whole body (13 patients) and separately for arms and legs (10 patients). RESULTS: Bioimpedance index (height(2)/impedance) and phase angle were lowe r in the undernourished group. Whole-body impedance declined (median, min-m ax) by 45, 1-151 Ohm after refeeding; the variations of bioimpedance index (BI-lndex) were weakly correlated (P <0.10) with BMI changes. Limb phase an gles increased with refeeding, but only changes in whole-body phase angle w ere correlated (P < 0.025) with the corresponding variations of Wt or BMI. CONCLUSION: Whole-body phase angle increased after weight recovery of anore xic patients, suggesting the occurence of modifications in the extracellula r-to-intracellular water ratio. These changes were proportional to the incr ease in BMI and Wt.