(A) shows the statistical mediation analysis for the associations of the lower Healthy Eating Index, more self-reported physical fatigability, on lower self-reported physical function through in a subset of 122 oldest-old participants from the Geisinger Rural Aging Study. (B) shows the statistical mediation analysis for the associations of the lower Healthy Eating Index—protein, more self-reported physical fatigability, on lower self-reported physical function through in a subset of 122 oldest-old participants from the Geisinger Rural Aging Study. The dependent (outcome) variable was set as the PROMIS19 Physical Function score, while the independent variable was set as the HEI total (A) or HEI protein (B), and the mediating variable was set as the Pittsburgh Fatigability Scale (PFS) Physical score. The models were also adjusted for the age group, sex, BMI, and the total number of medical conditions. The 95% confidence intervals (95% CI) were based on bootstrapping (1000 samples).