BODY-COMPOSITION CHANGES IN ANOREXIA-NERVOSA

Objective: To assess the body composition changes in anorexia nervosa and after medium term recovery. Design: A descriptive study. Setting: Rome, Italy. Subjects: Twenty women affected by anorexia nervosa (AN) with a EMI [weight (kg)/height (m(2))] below 17 kg/m(2) and weight-sta ble for at least three months, were compared with 10 well nourished co ntrol women (CO) and nine rehabilitated subjects (R-AN), who had a BMI above 18.5 kg/m(2) stable for at least the last six months. Intervent ions: Body fat was assessed by underwater weighing, muscle mass by uri nary creatinine, total body water (TBW) by impedance parameters (50 kH z and 800 mu A), skeletal mass by anthropometry and radius bone minera l density by dual photon absorptiometry in ultra-distal (UD-BMD) and m edio-distal (MD-BMD) sites. Results: The AN group, as compared to the control group, had a significantly lower weight, body mass index (BMI kg/m2) and percent body fat (P < 0.0000). Creatinine urinary excretion was lowest in absolute term and when expressed as creatinine height i ndex or per kg fat free mass (FFM) (P < 0.0000); muscle mass per kg bo dy weight was 13% lower (P < 0.01). Ultra distal bone mineral density (UD-BMD) was 6% lower (not significant). TBW as percent of body weight was significant higher (P < 0.001): however TBW/FFM % was not statist ically different with large inter-individual variability An altered di stribution of extra and intra-cellular water was suggested by the phas e angle (AN: 4.4 +/- 0.8 degrees; CO: 6.1 +/- 0.4 degrees (P < 0.0000) . In rehabilitated anorexic patients (R- AN) the fat mass represented 53% of the weight gain. Their creatinine excretion remained still belo w the mean value of the controls (P < 0.001). The impedance parameters were not significantly different between the R-AN and the CO groups, however, the phase angle of the R-AN (5.0+/-0.7 degrees) remained lowe r than in the CO group, indicating that the water distribution was sti ll altered. Conclusions: This study shows that AN is a condition of re duced body fat as well as of muscle mass, with a slightly reduced bone mass. In the course of rehabilitation, most of the weight regained is represented by fat, while the muscle mass appears to lag behind, at l east in the medium term.