Association Between Obesity Indices and Heart Rate Variability: A Cross‐Sectional Study in Asian Young College Students

Objective This study aimed to evaluate the associations of various traditional and novel obesity indices with heart rate variability (HRV) in Asian young college students, assessing their relative importance and potential sex differences. Methods In this cross‐sectional study of 3180 Asian young college students (mean age 19.6 years), we measured eight obesity indices including body mass index (BMI), waist circumference (WC), waist‐to‐height ratio (WHtR), and body fat percentage (BFP). HRV was assessed from a 5‐min resting electrocardiogram and analyzed across three autonomic domains derived from principal component analysis. We employed sex‐stratified linear models followed by a multimodel approach (best subset selection, relative importance analysis, and elastic net regression) to control for collinearity. All analyses were adjusted for age, heart rate, physical activity, and measurement time. Results BFP demonstrated the strongest associations with HRV parameters, showing significant negative correlation with SDNN (β = −1.76) and positive correlations with LF/HF (β = 0.123) and LFnorm (β = 1.84) (all FDR p < 0.001). Relative importance analysis showed that BFP contributed most to predicting LF/HF (38.1%), significantly exceeding WC (17.5%) and BMI (13.9%). The addition of BMI to BFP was associated with improved prediction for LF/HF and LFnorm (ΔR 2 > 0.03). Subgroup analysis showed that overweight/obese individuals with elevated BFP had significantly impaired HRV across all indices, while those with normal BFP showed reduced SDNN only. ROC analysis gave a BFP cutoff of 27.3% for identifying low HRV risk. No significant sex interactions were observed. Conclusion BFP was identified as the primary obesity indicator for autonomic function assessment in Asian young college students, while traditional indices (BMI, WC) provide valuable incremental information. Integrating body composition measurement into youth cardiovascular risk screening is recommended.