Results: Before CRC surgery, patients with serum NPY concentrations equal to or higher than the median value (661.70 pg/mL) had higher scores in their Mini Nutritional Assessment, Barthel, and Instrumental Activities of Daily Living (IADL) questionnaires, greater handgrip strength, a lower score in the Patient-Generated Subjective Global Assessment, and almost a three-times lower risk of perioperative complications, as well as higher Barthel and IADL scores and larger calf circumference at the 3-month follow-up visit in comparison to individuals with lower serum NPY concentrations. The gene discussed is NPY; the disease is colorectal carcinoma.