Sensitivity of Raw Bioimpedance Values to Acute Feeding in Healthy Young Adults: Potential Utility for Application

Impedance (Z), resistance (R), reactance (Xc), and phase angle (PhA) are sensitive to shifts in fluid between intra- and extracellular compartments, as would occur with nutrient uptake into skeletal muscle, but remains largely unexplored. To explore the sensitivity of whole-body and segmental (arms, legs, trunk) bioimpedance to acute feeding, 27 young adults completed three feeding conditions on separate occasions in randomized, cross-over design [high-carbohydrate (CHO), high-protein (PRO), fasted (FAST); standardized for fluid]. Bioimpedance was completed one-hour post-meal. Differences between feeding conditions at 5, 50, 250 kHz were evaluated. At 5 kHz, whole-body Xc and PhA were significantly different with CHO (p = 0.017), but not PRO (p = 0.152), compared to FAST; there were no significant differences at 50 or 250 kHz (p > 0.05). Segmental bioimpedance was significantly different with CHO and PRO compared to FAST [5 kHz: (Arms: Z, R, Xc,PhA; Trunk: Z, R; p = 0.002), 50 kHz:(Arms: Z, R, Xc; Trunk: Z, R, Xc; p < 0.02), 250 kHz:(Arms: Z, R; Trunk: Z, R; Legs: PhA; p = 0.009)]. Results suggest segmental bioimpedance at 5 kHz is sensitive to acute nutrition. Further exploration is warranted.