Objective To investigate the efficacy of dietary management based on the principles of enhanced recovery after surgery (ERAS) in bowel preparation for patients undergoing colonoscopy. Methods Patients undergoing colonoscopy procedures in the Department of Gastroenterology at West China Hospital, Sichuan University between December 2023 and December 2024 were randomly assigned to a control group and a trial group. The control group received conventional dietary management, comprising a self-prepared low-residue diet with fasting commencing at 22:00 on the preoperative evening. The trial group received dietary management based on the ERAS protocol, comprising pre-packaged low-residue meals on the day before surgery (lunch, dinner, and a 22:00 snack) plus 200 mL of clear liquids consumed 2 hours preoperatively. The Boston Scale and a subjective experience questionnaire (assessing preoperative and postoperative hunger, thirst, adverse reactions, etc.) were used to evaluate and compare bowel preparation quality and patient subjective experiences between the two groups. Results A total of 370 patients were included, comprising 194 in the control group and 176 in the trial group. Compared with the control group, the trial group showed no statistically significant difference in the Boston score for bowel preparation, the rate of adequate bowel preparation (78.41% vs. 71.65%), or the incidence of adverse reactions during bowel preparation or postoperatively (P>0.05). Patients in the trial group demonstrated higher subjective satisfaction with bowel cleansing (81.82% vs. 68.04%) and lower preoperative hunger [1.00 (0.00, 4.00) vs. 2.00 (0.00, 5.00)], with statistically significant differences (P<0.05). Conclusions Dietary management based on the ERAS concept does not increase the risk of bowel preparation failure or the incidence of adverse reactions during bowel preparation or postoperatively, compared with self-prepared low-residue diets. However, it reduces patients’ preoperative hunger and improves subjective satisfaction with bowel cleansing, making it worthy of promotion and application in clinical practice.