Abstract Introduction The prevalence of sarcopenia in CC patients undergoing colon cancer surgery is high and is associated with increased morbi-mortality. However, there are few studies assessing the impact of surgery on body composition. The main objective of this study was to analyze changes in body composition after colectomy for CC. Methods Observational, retrospective study in which patients operated on for CC by RICA route between December 2019 and June 2022 were collected. Pre- and post-surgical measurement of skeletal muscle index (SMI), Psoas iliacus index (PI), visceral adipose tissue (VAT) and subcutaneous adipose tissue (SAT) of each patient was performed by computed tomography (CT). In addition, the influence of previous nutritional assessment and postoperative supplementation on body composition variation was analyzed. Results After surgery, SMI, PI, VAT, and SAT significantly decreased in patients. Moreover, the number of patients with sarcopenia increased significantly. Although no statistically significant differences were identified, patients who did not receive preoperative nutritional supplementation exhibited a greater decrease in muscle mass and fat tissue, along with a higher tendency for postoperative complications. Conclusion Surgical intervention presents a negative impact on body composition in patients with CC with a significant decrease in muscle mass and visceral and subcutaneous fat. Preoperative nutritional optimization could buffer this loss with a consequent decrease in associated complications.