Despite multi-modal prehabilitation (nutrition, exercise, and psychosocial interventions), 60% of older elective colorectal cancer surgery patients with poor physical function were unable to reach a minimum preoperative 400m six-minute walking distance (6MWD), a prognostic cut-point. Compared to the patients that attained \>400m 6MWD preoperatively, twice as many of \<400m patients were malnourished. Malnutrition has long been associated with worse functioning (e.g., physical, immune). The investigators hypothesize that for nutritionally deficient patients, the etiology for their poor physical function is malnutrition. Correction of malnutrition alone might thus be sufficient to achieve a 400m 6MWD before surgery and improve patient outcomes.