Bioimpedance Spectroscopy: The Bioelectric Health Map in Tomorrow’s Medicine

The accelerated social changes of recent decades (urbanization, digitalization, transformation of dietary patterns, increased sedentary behavior, and chronic stress) have profoundly reconfigured the health profile of populations. Today, we face not only infectious or deficiency diseases, but a silent epidemic of non-communicable diseases (NCDs): obesity, type 2 diabetes, sarcopenia, osteoporosis, hidden malnutrition, and functional frailty¹. These conditions share a common denominator: subtle alterations in body composition that precede clinical manifestation by years².

 In this context, the medicine of tomorrow demands tools that go beyond weight, height, or BMI. We need to detect deterioration before it becomes irreversible. This is where bioimpedance spectroscopy (BIS) emerges as a key technology: it not only measures quantities but draws a bioelectric map of the functional state of living tissue³. 

What is the “bioelectric map”? 

BIS applies a range of frequencies (typically 1–1000 kHz) to the human body and analyzes its electrical response. Unlike single and multi-frequency bioimpedance, BIS allows for the adjustment of the Cole-Cole model, from which physiologically interpretable parameters are derived⁴: 

– R∞ (resistance at infinite frequency): reflects the conductivity of the total extracellular compartment. It decreases in overhydration or inflammation; it increases in relative dehydration or loss of lean mass⁵.

– C (membrane capacitance): quantifies the ability of cell membranes to store charge. It is a direct marker of cellular integrity, surface, and viability. It decreases with age, chronic inflammation, malnutrition, and loss of muscle mass⁶. 

– Re and Ri (extracellular and intracellular resistances): represent the dielectric properties of body fluids. Alterations in their ratio indicate fluid imbalances, expansion of the extracellular space, or loss of active cell mass⁷. 

Together, these parameters are not mere numbers; they constitute a dynamic map that reflects how modern lifestyles impact tissue architecture and function⁸, before clinical manifestations arise. 

BIS facing new health challenges 

Obesity and “hidden hunger”: Obesity is no longer just excess fat, but a state of low-grade inflammation and alteration of the extracellular compartment. BIS detects this phenomenon through changes in Re and R∞, even when BMI appears “normal”⁹. At the same time, it can identify hidden protein-calorie malnutrition in overweight individuals, characterized by low C and Ri, which BMI completely masks¹⁰. 

In this context, the potential relationship between membrane capacitance and insulin resistance takes on special relevance. The decrease in capacitance reflects alterations in the integrity and functionality of cell membranes, which can affect insulin-dependent transport and signaling mechanisms. Various studies suggest that states of low-grade chronic inflammation and expansion of the extracellular compartment, frequently associated with insulin resistance, are accompanied by changes in bioelectric parameters, including a reduction in capacitance. In this sense, BIS could provide complementary information for the early identification of metabolic alterations, even before evident glycemic changes manifest. 

Sarcopenia and frailty: Muscle loss is not only quantitative but qualitative; fibers are infiltrated with fat, and membranes deteriorate. Capacitance (C) progressively decreases, anticipating sarcopenia before the ASMI (appendicular skeletal muscle mass index), one of the diagnostic parameters, falls below the diagnostic threshold¹¹. This allows for preventive interventions with exercise and protein before disability sets in. 

Osteoporosis and fracture risk: Bone mass is not independent of muscle tissue or inflammatory status. Recent studies show that low capacitance and high Re are associated with lower bone mineral density, even in young adults¹². BIS, by integrating these domains, offers a systemic view of bone risk that goes beyond DEXA. 

Comprehensive monitoring: In rehabilitation, oncology, geriatrics, or sports nutrition, BIS allows for real-time monitoring of whether an intervention is improving tissue quality (↑C, ↓Re) or just moving water (transient changes in Re/Ri)¹³. This transforms outcome assessment into a precise science. 

Bioelectrical impedance analysis (BIA) has proven to be a valuable tool in assessing nutritional and functional status, thanks to parameters such as phase angle (PhA) and impedance ratio (IR). PhA, traditionally calculated at 50 kHz, reflects the relationship between capacitive reactance and ohmic resistance of the tissue and has been established as a sensitive marker of cellular integrity, muscle mass, and clinical prognosis in hospitalized, oncological, and geriatric populations^{14 15}. 

On the other hand, the IR —defined as the ratio between impedance at 200 kHz and at 5 kHz— has been used as an indirect indicator of fluid balance and body fluid distribution, showing utility in contexts of low-grade inflammation, fluid overload, and protein-calorie malnutrition^{16 17}. Although both parameters have been widely validated in multiple clinical scenarios, their dependence on fixed frequencies and their sensitivity to factors such as hydration have currently emerged as a limitation that must be considered in their interpretation¹⁸. 

Towards predictive and personalized medicine 

Future medicine will not wait for disease to appear. It will anticipate risk based on subclinical physiology. BIS, by offering a sensitive, reproducible, and non-invasive bioelectric map, positions itself as an essential tool in this transition¹⁹. 

It is not about replacing anthropometry or lab tests, but integrating them into a functional model where body composition is understood not as a static photo, but as a dynamic landscape shaped by lifestyle, genetics, and environment²⁰. 

At Aminogram, we believe technology must serve the person. That is why we promote the use of BIS not as a gadget, but as a bioelectric compass guiding earlier, more precise, and more humane clinical decisions. 

References

1. Norman K, et al. Bioelectrical phase angle and impedance vector analysis—Clinical relevance and applicability of impedance parameters. Clin Nutr. 2022;41(4):1023–1036. https://doi.org/10.1016/j.clnu.2021.12.012 ↩︎
2. Prado CM, et al. Redefining body composition assessment: quality over quantity. Clin Nutr. 2023;42(1):1–8. https://doi.org/10.1016/j.clnu.2022.11.015 ↩︎
3. Piccoli A. Bioelectric impedance measurement for fluid status assessment. Semin Nephrol. 2004;24(4):432–437. https://doi.org/10.1016/j.semnephrol.2004.06.009 ↩︎
4. Kyle UG, et al. Bioelectrical impedance analysis—Part I: Review of principles and methods. Clin Nutr. 2004;23(5):1226–1243. https://doi.org/10.1016/j.clnu.2004.06.004 ↩︎
5. González-Selgas M, et al. Extracellular water to total body water ratio as a marker of inflammation and mortality in older adults. Clin Nutr. 2022;41(7):1583–1590. https://doi.org/10.1016/j.clnu.2022.05.012 ↩︎
6. Lee SY, et al. Membrane capacitance measured by bioimpedance spectroscopy predicts clinical outcomes in older adults. Clin Nutr. 2023;42(5):1120–1127. https://doi.org/10.1016/j.clnu.2023.03.022 ↩︎
7. Bosy-Westphal A, et al. Quantification of whole-body and segmental skeletal muscle mass using phase-sensitive 8-electrode medical bioelectrical impedance devices. Curr Opin Clin Nutr Metab Care. 2021;24(5):431–439. https://doi.org/10.1097/MCO.0000000000000758 ↩︎
8. Lukaski HC, García-Almeida JM. Phase angle in applications of bioimpedance in health and disease. Rev Endocr Metab Disord. 2023;24(3):367–370. https://doi.org/10.1007/s11154-023-09799-0 ↩︎
9. Barrea L, et al. Phase angle: A biomarker for nutritional status and mortality in hospitalized patients. Clin Nutr. 2020;39(9):2890–2896. https://doi.org/10.1016/j.clnu.2020.01.004 ↩︎
10. Earthman CP. Body composition tools for assessment of adult malnutrition at the bedside: a tutorial on research considerations and clinical applications. JPEN J Parenter Enteral Nutr. 2015;39(7):787–822. https://doi.org/10.1177/0148607115571603 ↩︎
11. Di Vincenzo O, et al. Bioelectrical impedance analysis-derived phase angle in sarcopenia: A systematic review. Clin Nutr. 2021;40(5):3052–3061. https://doi.org/10.1016/j.clnu.2021.02.015 ↩︎
12. Dumitriu AM, et al. Advancing nutritional care through bioelectrical impedance analysis in critical patients. Nutrients. 2025;17(3):380. https://doi.org/10.3390/nu17030380 ↩︎
13. Brantlov S, et al. Cell membrane capacitance measured by bioimpedance spectroscopy: Clinical relevance and biomarker potential. Sensors. 2025;25(14):4362. https://doi.org/10.3390/s25144362 ↩︎
14. Norman K, et al. Bioelectrical phase angle and impedance vector analysis—Clinical relevance and applicability of impedance parameters. Clin Nutr. 2022;41(4):1023–1036. https://doi.org/10.1016/j.clnu.2021.12.012 ↩︎
15. Yang J, et al. Bioelectrical impedance phase angle and mortality in critically ill children. Front Nutr. 2024;11:1359814. https://doi.org/10.3389/fnut.2024.1359814 ↩︎
16. Miranda-Alatriste PV, et al. Hydration status according to impedance vectors and its association with clinical and biochemical outcomes and mortality in patients with chronic kidney disease. Nutr Hosp. 2022;39(5):111–120. https://doi.org/10.20960/nh.03970 ↩︎
17. Ward LC, Cornish BH. Bioelectrical impedance analysis: An overview. Australas Phys Eng Sci Med. 2004;27(1):1–11. https://doi.org/10.1007/BF03178584 ↩︎
18. Bellido D, García-Almeida JM. ¿Por qué debemos incorporar la determinación del ángulo de fase por impedancia bioeléctrica a nuestra práctica habitual en nutrición clínica? Nutr Hosp. 2024;41(2). https://doi.org/10.20960/nh.05230 ↩︎
19. Piccoli A. Bioelectric impedance measurement for fluid status assessment. Semin Nephrol. 2004;24(4):432–437. https://doi.org/10.1016/j.semnephrol.2004.06.009 ↩︎
20. Prado CM, et al. Redefining body composition assessment: quality over quantity. Clin Nutr. 2023;42(1):1–8. https://doi.org/10.1016/j.clnu.2022.11.015 ↩︎