During a bioelectrical impedance analysis (BIA), if a person is over hydrated, how might their body fat percentage appear?

In a bioelectrical impedance analysis (BIA), the device measures the resistance encountered by electrical signals as they pass through body tissues. Hydration levels significantly influence these readings. When an individual is over-hydrated, excess water in the body leads to a lower resistance to electrical flow, which can cause the device to misinterpret this condition as a sign of lower body fat percentage.

This misleading result occurs because BIA assumes a certain ratio of fat mass to lean mass. Since fat tissue contains less water than lean tissue, increased total body water can skew the calculations typically used to determine body fat percentage. Consequently, the body fat percentage may appear lower than it actually is, as the excess water inflates the lean mass measurement. Understanding this relationship is crucial for accurate body composition assessment and underscores the importance of considering hydration status before conducting a BIA test.