BACKGROUND: Weight change offers the simplest indication of a patient's recovery after an operation. There have been no studies that have thoroughly investigated postoperative weight dynamics after pancreatectomy. The aim of this study was to define postoperative weight change after a pancreatectomy and determine factors associated with optimal and poor weight trajectories. METHODS: From 2004 to 2019, 1,090 proximal (65%) and distal (35%) pancreatectomies were performed in patients with adequate data in the medical records. Patient weights were acquired preoperatively and at postoperative months 1, 3, and 12. Optimal (top quartile, weight restoration) and poor (bottom quartile, persistent weight loss) postoperative weight cohorts were identified at 1 year postoperatively. RESULTS: The median percentage weight change 1 year postpancreatectomy was -6.6% (interquartile range: -1.4% to -12.5%), -7.8% for proximal pancreatectomy, and -4.2% for distal pancreatectomy. For most patients (interquartile range cohort), the median percentage weight change at 1, 3, and 12 months was -6.2%, -7.2%, and -6.6%. The independent factors associated with weight restoration were age <65, nonobesity (body mass index <30kg/m2), receiving total parenteral nutrition/total enteral nutrition preoperatively, experiencing preoperative weight loss >10%, distal pancreatectomy, not undergoing vascular resection, and no readmission within 30 days. Conversely, persistent weight loss was associated with American Society of Anesthesiologists classes III to IV, obesity, malignancy, proximal pancreatectomy, blood loss ≥350mL, and experiencing readmission within 30 days. Focusing on pancreatic ductal adenocarcinoma (n = 372) patients, the factors associated with persistent weight loss were obesity, proximal pancreatectomy, and experiencing recurrence within 1 year; however, weight cohorts were not associated with overall survival for pancreatic ductal adenocarcinoma patients. CONCLUSION: These data define weight kinetics after pancreatectomy. Ultimately, postoperative weight trajectories appear to be largely predetermined but may be mitigated by limiting readmissions and complications. Clinicians should use these data to identify patients who continue to lose weight between the first and third month postoperatively with a high suspicion for the requirement of nutritional monitoring or other interventions.