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Bioelectrical Impedance Analysis (BIA)
Body composition technique that estimates total body water, fat-free mass, and fat mass from electrical resistance and reactance to a low-amplitude alternating current passed through the body.
Also: BIA
BIA uses the principle that lean tissue conducts current more readily than fat. Single-frequency, multifrequency, and bioimpedance spectroscopy vary in accuracy. BIA is portable, inexpensive, and noninvasive, but estimates are model- and hydration-dependent; phase angle (a direct BIA-derived variable) has independent prognostic value in malnutrition and disease. MNHD treats BIA as a screening tool rather than a reference method.
How each textbook covers it
Krause and Mahan's Food and the Nutrition Care Process, 16th ed. — Chapter 5
BIA exploits the different electrical conductivity of lean tissue (high water, high conductivity) and fat (low water, low conductivity). Results depend heavily on hydration status, recent food intake, and recent exercise, so measurement conditions must be standardized. Used in clinical settings to track body composition in HIV, cancer, and obesity care.
Modern Nutrition in Health and Disease, 12th ed. — Ch 47: Body Composition
BIA uses the principle that lean tissue conducts current more readily than fat. Single-frequency, multifrequency, and bioimpedance spectroscopy vary in accuracy. BIA is portable, inexpensive, and noninvasive, but estimates are model- and hydration-dependent; phase angle (a direct BIA-derived variable) has independent prognostic value in malnutrition and disease. MNHD treats BIA as a screening tool rather than a reference method.
Related terms
Body Composition, DEXA, DXA, GLIM criteria, Lean Body Mass, Sarcopenia