Association of Korean Healthy Eating Index with Phase Angle and Extracellular Water-to-Total Body Water Ratio: Findings from a Nationally Representative Study.
Dietary quality, assessed using the Korean Healthy Eating Index, was positively associated with phase angle and negatively associated with the extracellular water-to-total body water ratio in a nationally representative sample of Korean adults.
Key Findings
Results
Higher Korean Healthy Eating Index (KHEI) scores were associated with higher phase angle in a dose-response pattern across quartiles.
In the fully adjusted model, β (95% CI) values for phase angle were 0.04 (0.01, 0.07), 0.06 (0.02, 0.09), and 0.08 (0.04, 0.11) for Q2, Q3, and Q4, respectively, compared to Q1.
The association was statistically significant for all three higher quartiles compared to the lowest quartile.
The mean phase angle in the sample was 5.37° (SD: 0.80°).
KHEI scores range from 0 to 100, with higher scores indicating better dietary quality.
Results
Higher KHEI scores were associated with a lower extracellular water-to-total body water (ECW/TBW) ratio in a dose-response pattern across quartiles.
In the fully adjusted model, β (95% CI) values for ECW/TBW ratio were -0.03 (-0.07, -0.00), -0.06 (-0.09, -0.02), and -0.07 (-0.10, -0.03) for Q2, Q3, and Q4, respectively, compared to Q1.
The mean ECW/TBW ratio in the sample was 38.19% (SD: 0.79%).
The association was statistically significant across all higher quartiles.
Methods
The study was conducted using a nationally representative sample of 12,162 Korean adults.
Sample size was n = 12,162 adults from the Republic of Korea.
The study design was cross-sectional.
Dietary quality was assessed using the KHEI and categorized into quartiles.
Phase angle and ECW/TBW ratio were measured using a bioelectrical impedance analyzer.
Linear regression models were used to analyze associations, with results reported as beta coefficients and 95% confidence intervals.
Background
Phase angle and ECW/TBW ratio derived from bioelectrical impedance analysis were examined as biomarkers in relation to dietary quality.
Phase angle is a bioelectrical impedance analysis-derived measure that has attracted interest as a biomarker.
The ECW/TBW ratio is also derived from bioelectrical impedance analysis and has attracted interest as a biomarker.
The mean phase angle was 5.37° (SD: 0.80°) and mean ECW/TBW ratio was 38.19% (SD: 0.79%).
Conclusions
The authors concluded that longitudinal studies are needed to confirm the temporal relationships between dietary quality and these bioelectrical impedance biomarkers.
The cross-sectional design prevents establishment of temporal or causal relationships.
The authors explicitly called for longitudinal studies to confirm the observed associations.
Findings showed dietary quality was positively associated with phase angle and negatively associated with ECW/TBW ratio.
What This Means
This research suggests that the quality of a person's diet is linked to two body composition measures obtained from a type of body scan called bioelectrical impedance analysis (BIA). The study looked at over 12,000 adults in South Korea and found that people who ate healthier diets — as measured by the Korean Healthy Eating Index — tended to have higher 'phase angle' readings and lower 'extracellular water-to-total body water' (ECW/TBW) ratios. Phase angle is thought to reflect cell health and membrane integrity, while ECW/TBW ratio reflects how water is distributed in the body, with higher values potentially indicating fluid retention or poorer cellular function. Both are considered potential health biomarkers.
The associations followed a consistent dose-response pattern: the better the diet quality, the more favorable the biomarker values, even after accounting for other factors that might influence the results. Importantly, the effect sizes, while statistically significant, were relatively small in absolute terms, and because the study measured diet and body composition at a single point in time, it cannot prove that better diet causes better biomarker values — only that the two are related.
This research suggests that dietary habits may play a role in maintaining cellular health and fluid balance as measured by BIA-derived indicators. However, the authors note that longer-term studies following people over time are needed to understand whether improving diet quality actually leads to improvements in these biomarkers, and what the clinical significance of such changes might be.
Check Your Own Numbers
Upload your bloodwork. We'll cross-reference your results against this study and 4,700 others.
Baek S, Yoon J. (2026). Association of Korean Healthy Eating Index with Phase Angle and Extracellular Water-to-Total Body Water Ratio: Findings from a Nationally Representative Study.. Nutrients. https://doi.org/10.3390/nu18193213