Short-Term Changes in Segmental Multi-Frequency Bioelectrical Impedance Measurements Following Water and Banana Intake: A Fixed-Order Within-Subject Study.

Background: Bioelectrical impedance analysis (BIA) is widely used for body composition assessment but may be influenced by hydration status and recent food intake. This study evaluated short-term changes in segmental multi-frequency BIA measurements following water and banana intake. Methods: Ninety-eight healthy adults (54 women, 44 men; 21-33 years) underwent BIA measurements at baseline and at 30, 60, and 90 minutes after consuming 600 mL of water on the first experimental day and 300 g of banana on the second day. The study used a fixed-order within-subject repeated-measures design. Post-ingestion values were analyzed using baseline-adjusted linear mixed-effects models with participant-specific random intercepts. Holm's procedure was applied across the five time × experimental condition/day interaction tests. Results: Significant time × experimental condition/day interactions were not observed for body fat percentage, total body water percentage, or trunk impedance at 20 or 100 kHz (all unadjusted p ≥ 0.133). A significant interaction was observed for visceral fat area estimate (F(2,194) = 8.532, unadjusted p < 0.001; Holm-adjusted p < 0.005). The largest adjusted between-condition/day difference in visceral fat area estimate was 0.858 cm² at 30 minutes. Because intake condition was fixed by study day, condition effects could not be separated from potential day or order effects. Conclusions: Under the fixed-order conditions examined, temporal responses were similar between experimental days for most SMF-BIA outcomes, while a small interaction was observed for visceral fat area estimate. These findings require confirmation in randomized, counterbalanced studies including a no-intake control condition.