Body mass index having a mediating role between diet quality & mental and physical health among women

Abstract

Background: Women experience unique dynamics in health and Quality of Life (QoL) due to biological, psychological, and social factors. These dynamics necessitate a comprehensive examination of the indirect effects of Diet Quality (DQ) on Mental and Physical well-being through Body Mass Index (BMI). This study aims to elucidate the indirect pathways through which DQ influences mental and physical well-being, with a particular focus on the mediating role of BMI. Methods: This cross-sectional study was conducted with women (n = 985) aged 19–64 years. Anthropometric measurements and 24-Hour Dietary Recall (24HDR) data were collected. QoL was assessed using the Short Form-36 (SF-36), which comprises two primary subdimensions: (1) Mental Well-being, represented by the Mental Component Summary (MCS), and (2) Physical Well-being, represented by the Physical Component Summary (PCS). The Nutrient-Based Diet Quality Index (NBDQ) and Carbohydrate-to-Fibre Ratio (CHO-FBR) were calculated from 24HDR data to evaluate DQ. Two mediation models were employed. Model 1 examined the indirect effects of NBDQ on Mental and Physical well-being through BMI, with age as a confounder. Model 2 assessed the indirect effects of CHO-FBR on Mental and Physical well-being through BMI, also considering age as a confounder. Results: The mean age of participants was 31.68 ± 11.95 years. No significant differences were found in educational attainment across DQ quartiles (p = 0.228). Younger women (19–24 years) were more prevalent in lower DQ quartiles, while older women (45–64 years) showed higher DQ scores (p = 0.001). Women with spouses had higher DQ (p = 0.007). MCS score improved with a better NBDQ (p = 0.033), although PCS score did not show significant difference (p = 0.607). Mediation analysis revealed that NBDQ was significantly associated with MCS (β = 0.169, p = 0.004) but not with BMI (β = 0.004, p = 0.568). Aditionally, NBDQ showed a non-significant relationship with PCS (β = -0.022, p = 0.505). Conclusion: Improving DQ can enhance mental well-being (MCS), particularly among older women and those with spouses, while no impact was found on physical well-being (PCS). Since BMI did not mediate these effects and CHO-FBR showed no significant associations, nutritional strategies should prioritize DQ alongside age and social dynamics to effectively enhance women’s QoL.