Runas Journal of Education and Culture · Oct 8, 2026
Relationship of fat mass index and fat-free mass index with body mass index and association with physical function, cognition, and nutritional status in older adults in rural areas of Ecuador
By Paredes DFR, Contreras FHS, Martínez FEL
Body mass index (IMC) does not distinguish between fat mass and fat-free mass or account for adipose tissue distribution, which limits its usefulness as a marker of health status in older adults. The objective was to evaluate the relationship of IMC with fat mass index (FMI), fat-free mass index (FFMI), and the fat mass/fat-free mass ratio (MG/MLG), and to study their association with physical function, cognitive status, and nutritional status in rural older adults. A cross-sectional study was conducted in 302 older adults (?65 years) from the rural parishes of Sinincay, Ricaurte, and El Valle (Cuenca, Ecuador). Body composition was measured by bioelectrical impedance analysis (BIA), and the Mini Nutritional Assessment (MNA), Yesavage Geriatric Depression Scale, Mini-Mental State Examination (MMSE), Tinetti Scale (gait and balance), and Lawton and Brody Instrumental Activities of Daily Living Scale were administered. FMI, FFMI, and MG/MLG were classified into tertiles (T1 lowest, T3 highest) and stratified by IMC. The mean age was 74.2 ± 7.6 years; 67.9% were women. The highest tertile of FMI and the MG/MLG ratio was associated with greater chronological and body age, greater visceral fat, and worse total Tinetti Scale scores (p=0.043 and p=0.046, respectively). The highest FFMI tertile was associated with lower body age, greater muscle mass, and better MMSE scores (p=0.001). The MNA score did not differ significantly between tertiles of any of the three indices. In the adjusted linear regression analysis, FMI was the only independent predictor of the total Tinetti score (?=?0.193; IC95% ?0.384 to ?0.002; p=0.048). In rural older adults in Cuenca, greater relative adiposity (FMI and the MG/MLG ratio) is associated with impaired balance and gait measured by the Tinetti Scale, whereas greater fat-free mass (FFMI) protects cognitive function. FFMI and the MG/MLG ratio are better predictors of functional and cognitive status than IMC alone. Interventions aimed at increasing fat-free mass could reduce the risk of falls and cognitive impairment in this population.