(41) Relationship Between Dietary Intake, Energetic Status, and Whole-Body Bioelectrical Impedance Values

Purpose: Raw bioimpedance analysis (BIA; resistance [R], reactance [Xc], and phase angle [PhA]) reflects cellular health and body composition, which can be influenced by dietary intake and energy status (ES). Currently used to help assess nutritional status in clinical populations at risk for malnutrition, BIA may also be useful for assessing nutritional status in active individuals, particularly those at risk for negative health and performance consequences due to low energy availability or inadequate ES. Despite potential to serve as a simple, rapid tool to assess ES and dietary intake, research on the application of raw bioimpedance to assess nutrition and ES in active individuals, and especially in women, is limited. Therefore, the purpose of this study is to explore relationships between dietary intake (calories [CAL], protein [PRO], carbohydrates [CHO], fats [FAT]), ES (daily energy need to caloric intake), and whole-body BIA (R, Xc, PhA) in recreationally active women. Methods: Healthy, recreationally active women (EUM=17; IUD=9; OC=11) (Mean±SD; Age: 22.9±4.0; %BF: 25.8±5.7%) completed whole-body BIA (R, Xc, PhA) and resting metabolic rate (RMR via indirect calorimetry) in the low (LHP; 1-7 days post menstruation/placebo) and high hormone phase (HHP; 5-9 days post ovulation/active pill). Urinary estrogen (E) was assessed on visit days. Dietary intake (CAL, CHO, FAT, PRO) was analyzed from prior-day food log. ES was calculated as the ratio between daily energy need (RMR adjusted with a moderate exercise activity factor of 1.55) and total reported caloric intake. Paired t-tests assessed differences in measured variables between LHP and HHP. Pearson’s correlations examined relationships between dietary intake, ES, and raw BIA values. Regression analyses evaluated the relationship between outcomes by phase, covaried for E levels. Results: Estrogen was significantly higher in the HHP (p >0.001), while all other variables did not differ between phases (p=0.086-0.874). In LHP, PhA was negatively correlated with FAT (r=-0.328, p=0.048), while in HHP, PhA was positively correlated with PRO (r=0.417, p=0.010). No other significant correlations were found between R, Xc, PhA and CAL, CHO, FAT, PRO, or ES (r=0.011-0.264, p=0.078-0.995). Regression analyses controlling for E indicated that PRO in HHP significantly predicted PhA (β=0.005, p=0.033, R²=0.240). No significant associations were found between R, Xc, and dietary intake or ES (p=0.150-0.983). Conclusions: While macronutrient intake did not differ between phases, PhA relationships with FAT and PRO were phase-dependent, potentially related to hormonal effects on substrate metabolism and cellular function. Higher FAT intake in LHP may be linked to lower cellular integrity, while higher PRO intake in HHP may be important for supporting cellular health and integrity when hormones are elevated. While exploratory, these findings suggest that the relationship between macronutrient intake and PhA may vary across hormonal phases. Practical Applications: Raw BIA, particularly PhA, can be an effective, non-invasive tool for monitoring cellular health in active women. Tracking PhA across menstrual phases may help guide dietary strategies to optimize performance, recovery, and well-being, particularly for those with hormone-related changes. Results suggest reducing excessive FAT intake in LHP and emphasizing PRO in HHP may support cellular integrity; further research is needed to confirm these findings. Acknowledgements: None