Phase Angle in Bioelectrical Impedance: New Perspectives in Health and Body Composition Assessment.

Mean phase angle values were significantly higher in men than in women.

• Mean PhA was 6.29° in men versus 5.57° in women (p < 0.001).
• The study included 265 participants (122 women and 143 men) aged 18–77 years.
• Participants were examined at a nutritional outpatient clinic in Prague between April 2022 and December 2023.
• Segmental multi-frequency BIA was performed using the Tanita MC-780 MA analyzer with eight electrodes at frequencies of 5 kHz, 50 kHz, and 250 kHz.

A strong negative correlation between the extracellular water-to-total body water ratio (ECW/TBW) and phase angle was observed in men, while the correlation was moderate in women.

• In men, the correlation between ECW/TBW and PhA was r = -0.78 (p < 0.001).
• In women, the correlation between ECW/TBW and PhA was r = -0.33 (p < 0.001).
• The sex-based difference in the strength of this correlation suggests different physiological determinants of PhA between men and women.

A strong positive correlation between phase angle and intracellular water (ICW) volume was observed in women, while the association was weaker in men.

• In women, the correlation between PhA and ICW was r = 0.71 (p < 0.001).
• In men, the correlation between PhA and ICW was r = 0.17 (p < 0.05).
• This pattern suggests that in women, muscle mass (reflected by ICW) is the dominant factor influencing PhA.

The key determinants of phase angle differ by sex, with fat mass (particularly visceral fat) predominating in men and muscle mass predominating in women.

• In men, fat mass and visceral fat were identified as predominant determinants of PhA.
• In women, muscle mass was identified as the dominant factor influencing PhA.
• These sex-specific differences were reflected in the differing patterns of correlation with ECW/TBW and ICW between men and women.

Phase angle was significantly correlated with body fluid distribution and body composition parameters across the study sample.

• The study was observational, descriptive, and cross-sectional in design.
• 265 healthy adult participants were included, aged 18–77 years.
• PhA is described as 'a valid, non-invasive marker of body composition, sensitive to changes in internal milieu, with potential clinical applications for assessing nutritional status and the patient's physiological condition.'
• Correlations were assessed across both sexes using segmental multi-frequency BIA.