Early Lean Tissue Loss and Nutritional Challenges Following Sleeve Gastrectomy in a Kidney Transplant Recipient: A Case Report.

Background/Objectives: Obesity after kidney transplantation impairs graft function, but the time course of lean tissue loss after sleeve gastrectomy in this population is poorly described. Methods: A 46-year-old woman underwent sleeve gastrectomy five years after kidney transplantation and was followed for 33 months with bioelectrical impedance analysis (BIA) and three 24-h dietary recalls per visit. Results: Weight fell from 103.4 to 69.4 kg by month 6, with mild regain to 71.9 kg at month 33. BIA-derived fat-free mass, BIA-predicted total muscle mass and BIA-derived skeletal muscle mass reached their lowest recorded values at month 3, each 21.3% below baseline, and were essentially unchanged at month 6; fat-free mass loss corresponded to 34.1% of the weight lost by month 6, above the thresholds proposed for excessive loss in a bariatric cohort which are research rather than clinical definitions. This early loss coincided with three concurrent exposures: energy restriction (521 and 466 kcal/day at months 1 and 3), protein intake below target during a period of aversion to protein-rich foods (33.2 g/day against a 60 g/day target), and absence of structured physical activity; anaemia was present throughout and may have contributed to both. Graft function was clinically stable but not unchanged, with estimated glomerular filtration rate 25% below baseline at month 33 and persistent proteinuria; biopsy was not performed. Conclusions: Early postoperative nutritional vulnerability was temporally associated with substantial lean tissue loss. The estimates are BIA-derived and hydration-dependent, muscle function was not assessed, and the concurrent exposures cannot be separated in a single case, so no causal relationship can be inferred.