Kidney transplantation (KT) experts did not support the use of subjective unintentional weight loss to measure shrinking in the Physical Frailty Phenotype (PFP); a clinically feasible and predictive measure of shrinking is needed. To test whether unintentional weight loss could be replaced by an assessment of sarcopenia using existing CT scans, we performed a prospective cohort study of adult KT recipients with original PFP (oPFP) measured at admission (12/2008-2/2020). We ascertained sarcopenia by calculating skeletal muscle index from available, clinically obtained CTs within 1-year pre-KT (male<50cm2/m2; female<39cm2/m2) and combined it with the original 4 components to determine new PFP (nPFP) scores. Frailty was classified by frailty score: 0:non-frail;1-2:pre-frail;≥3:frail. Mortality and graft loss hazard ratios (HRs) were estimated using adjusted Cox proportional hazard models. Model discrimination was quantified using Harrell’s C-statistic. Among 1,113 recipients, 18.6% and 17.1% were frail by oPFP and nPFP, respectively. Compared to non-frail recipients, frail patients by either PFP had higher risks of mortality (oPFP HR=1.67,95%CI:1.07-2.62,C=0.710; nPFP HR=1.68,95%CI:1.06-2.66,C=0.710) and graft loss (oPFP HR=1.67,95%CI:1.17-2.40,C=0.631; nPFP HR=1.66,95%CI:1.15-2.40,C=0.634) with similar discriminations. oPFP and nPFP are equally useful in risk prediction for KT recipients; oPFP may aid in screening patients for pre-KT interventions, while nPFP may assist in nuanced clinical decision-making.