Using Bioelectrical Impedance Analysis to Assess Body Composition Changes in Female Patients with Anorexia Nervosa (AN) during Physical Recovery

Assessment of physical recovery in individuals with anorexia nervosa (AN) has traditionally relied on weight and body mass index (BMI), yet these measures lack the nuance needed to reflect physical recovery. Bioelectrical impedance analysis (BIA) offers a promising, non-invasive method for tracking physiological changes during nutritional rehabilitation. This narrative review evaluates the use of BIA in assessing body composition changes in female patients with AN during nutritional rehabilitation. Peer-reviewed studies published between 2019 and 2024 reporting BIA-derived body composition data in females with AN were identified. Studies included hospitalized and outpatient patient populations across various stages of illness and recovery. Data on baseline and follow-up measurements were compared and evaluated. Four studies met the inclusion criteria. All 4 studies reported significant improvements in weight and BMI in the participants. Bioelectrical impedance analysis detected subtle physiological changes not captured by weight and BMI alone. Increases in fat mass (FM) and fat-free mass (FFM) and improvements in phase angle (PhA) were reported during weight restoration interventions. Preliminary evidence suggests that BIA is reliable for monitoring body composition during AN treatment. However, small sample sizes and heterogeneous study populations warrant cautious application of the findings. Larger, more inclusive studies are needed to support broad clinical use of BIA in AN recovery.