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 populations14 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 malnutrition16 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.
