12271 Differential Impacts Of Body Composition Indices On Cortisol Response And Hpa Axis Activity

Abstract Disclosure: S.G. Gonsalves: None. A. Ross: None. M.E. Steele: None. L.N. Saligan: None. Aim: The continued interest in the influence of muscle mass and fat distribution on stress stems from its implications on preventative healthcare. Fat mass index (FMI) and fat-free mass index (FFMI) were proposed as valuable indicators of body composition beyond body mass index (BMI). This study investigated correlations of FMI and FFMI with inflammatory stress markers, hypothesizing that these body composition indices identify inflammatory stress markers more distinctly than BMI. Methods: Skeletal muscle mass was assessed by Dual-Energy X-ray Absorptiometry, HPA axis response through an adrenocorticotropic hormone (ACTH) stimulation test, and markers of inflammation and stress response (e.g., dehydroepiandrosterone, DHEA) from peripheral blood of 104 healthy individuals aged 18-71 years, 52% female, with a mean BMI of 26.3 (+4.83). Perceived stress and fatigue were captured using patient-reported outcome questionnaires before the HPA procedure. Results: ACTH correlated with FFMI at baseline (ρ=0.299, p=0.009) and 60 minutes (ρ=0.254, p=0.041). Cortisol correlated with FFMI at 15 (ρ=–0.248, p≤0.025), 30 (ρ=–0.284, p≤0.010), and 60 minutes (ρ=–0.364, p≤0.001), and with BMI at 15 (ρ=–0.228, p=0.041). FMI and BMI did not correlate with ACTH and FMI with cortisol at any timepoint. With repeated measures ANOVA, FFMI at 50th percentile had large effect on cortisol (p=0.005, partial eta=0.094) at each timepoint, higher for the under lean than those with higher FFMI, compared to BMI at the same percentile (p=0.037, partial eta=0.054). None of the indices reached significance with ACTH. FMI correlated with Erythrocyte Sedimentation Rate (ESR) (ρ=0.521), C-reactive protein (CRP, ρ=0.493, both at p≤0.001), DHEA (ρ=0.252, p=0.030), and epinephrine (ρ=–0.246, p=0.045). FFMI was not correlated with ESR and CRP. BMI correlated only with albumin (ρ = –0.412, p ≤ 0.001 and CRP (ρ=0.342, p≤0.003). Discussion: The higher correlations of inflammatory stress markers with FMI and FFMI, as compared to BMI, supports our study hypothesis. These results hint that these body composition indices may detect subtle stress-related inflammatory changes than BMI. Future research should clarify underlying mechanisms driving these associations and explore the impact of targeted interventions on these indices and subsequent changes to inflammation and stress. Presentation: 6/1/2024