<b><i>Background/Aims:</i></b> The aim of the current study was to assess the postoperative evolution of nutritional status and to relate it with postoperative outcomes. <b><i>Methods:</i></b> Demographic, surgical and nutritional parameters were assessed 10 days preoperatively (d-10) and 30 days postoperatively (d30) in 146 patients. Risk factors responsible for perioperative (>5% between d-10 and d30) weight loss were identified. Overall, severe (Clavien 3-5) and infectious complications were compared in patients with and without perioperative weight loss (>5%). <b><i>Results:</i></b> Nutritional status worsened beyond the postoperative period as reflected by decreasing weight (67 ± 13 kg at d-10 vs. 63 ± 13 kg at d30, p < 0.001), body mass index (23.4 ± 4 vs. 22.2 ± 4 kg/m², p < 0.001) and mid upper-arm muscle circumference (MAMC, 241 ± 32 vs. 232 ± 30 mm, p < 0.001). Fifty-two patients (46%) lost >5% of their body weight between d-10 and d30. Patients who presented overall (63 vs. 36%, p = 0.004) and major (27 vs. 10%, p = 0.016) postoperative complications were at significantly higher risk to deteriorate postoperative nutritional status. Multivariate analysis identified low preoperative lean body mass (OR 3.2; 95% CI 1.2-8.9, p = 0.023) and low preoperative MAMC (OR 2.5; 95% CI 0.9-6.8, p = 0.066) as independent risk factors for perioperative weight loss. <b><i>Conclusions:</i></b> These data suggest continuing nutritional follow-up after the index hospitalization.