Colorectal cancer patients with a muscle loss phenotype face significantly worse postoperative outcomes.

• Muscle loss nearly triples the risk of complications (odds ratio 2.99) and doubles the chance of unfavorable discharge (odds ratio 2.42).
• Prolonged hospital stays are common, with an odds ratio of 4.34, leading to higher total costs by over $70 per hospitalization.

Surgeons should prioritize muscle loss assessments preoperatively to better predict risks and tailor interventions.

• Muscle loss is most associated with severe complications like shock, sepsis, and respiratory failure.