Rodrigues, FilipeMonteiro, DiogoMonteiro, A. M.Forte, Pedro2026-02-052026-02-052026-02-02Rodrigues, F., Monteiro, D., Monteiro, A. M., & Forte, P. (2026). Interactions Between BMI and Age on Fall Risk in Older Adults. Epidemiologia, 7(1), 18. https://doi.org/10.3390/epidemiologia7010018http://hdl.handle.net/10400.8/15541Background/Objectives: The aging process is typically marked by a reduction in functional fitness, which heightens the likelihood of falling. Although obesity is established as a determinant of poor mobility, the interplay between excess weight and advanced age is still a topic of research interest. Therefore, this research investigated how age, sex, and Body Mass Index (BMI) interact to influence fall risk among older adults living in the community. Methods: This cross-sectional investigation involved 815 participants (Mage = 70.45 ± 6.10 years), stratified by age (sexagenarians, septuagenarians, octogenarians) and BMI (normal weight, overweight, obesity). Fall risk was assessed using the Timed Up and Go test. A Three-Way ANOVA examined the main and interaction effects. Results: No significant three-way interaction (p = 0.334) or main effect of sex (p = 0.079) was found. However, a significant age x BMI interaction was observed (p = 0.007). In sexagenarians and septuagenarians, obesity was associated with significantly slower fall risk performance compared to normal weight (p < 0.001). Conversely, in octogenarians, this difference was not significant (p = 1.000) with normal-weight individuals. Conclusions: Obesity may be a significant risk factor for falls, especially in adults aged 60 to 79 years. In octogenarians, the protective benefit of normal weight disappears, revealing a “weight paradox” likely driven by sarcopenia. Fall risk assessments and weight management strategies should be tailored to age, focusing on preserving muscle mass in octogenarians.engfunctional fitnessagingobesity paradoxsarcopeniafall riskresearch article2026-02-02cv-prod-470464610.3390/epidemiologia7010018