Bioimpedance: From Body Composition Assessment to Emerging Technologies in Clinical Nutrition

This review examines the physical foundations, predictive models, emerging technologies and recent research trends in bioimpedance for clinical nutrition. A bibliometric analysis of cumulative scientific production from 1980 to 2025 shows that weighted logistic models provide a good descriptive fit to the evolution of the literature (R² ≥ 0.999). Bioimpedance research remains in an expanding phase, with its projected inflection point lying beyond 2026. These fits are descriptive and model-dependent: high coefficients of determination on cumulative counts are not in themselves evidence of predictive validity, and inflection points beyond the observation window are extrapolations. We introduce the Measurement-Independent Factor (MIF), which isolates the anthropometric contribution from the bioimpedance measurement in predictive equations. Phase Angle (PhA) has emerged as the most extensively studied bioimpedance descriptor, since it avoids the population-specific prediction equations required for estimates such as FFM or FM, although its absolute value remains dependent on measurement conditions, instrumentation and biological characteristics. Body-composition estimates obtained with devices from different manufacturers should not be interpreted interchangeably. Electrode technologies, bioimpedance wearables, and bioimpedance imaging are reviewed as major emerging research directions. A second bibliometric analysis covering the most-cited literature from 2020 to 2026 and 1655 original articles published during 2025-2026 show that recent research focuses primarily on obesity and adiposity, together with sarcopenia and frailty, whereas critical and acute care remain underrepresented.