Safety and Efficacy of Leucine-Restricted Diet in Gastric Cancer

Inclusion Criteria: * Pathologically confirmed gastric carcinoma requiring preoperative endoscopic localization marking or delineation of the lesion extent. * Aged between 18 and 70 years, regardless of gender. * Ability to consume oral or nasogastric tube feeding of a liquid diet. * Provision of signed informed consent and voluntary participation in this study. * No evidence of distant metastasis on preoperative imaging studies (e.g., CT, PET-CT), and deemed suitable for surgical resection. * No concurrent diagnosis of other active malignancies. Exclusion Criteria: * Presence of cognitive impairment or psychological disorders that may compromise the understanding of the research content. * Diagnosis of Type I or Type II Diabetes Mellitus. * Severe diarrhea, intractable vomiting, severe malabsorption syndromes, paralytic or mechanical intestinal obstruction, or active gastrointestinal bleeding. * Known allergy to the primary components of the leucine-deficient nutritional formula. * Concurrent use of other nutritional supplements that may interfere with the trial's efficacy. * Postoperative pathological diagnosis confirming non-primary gastric cancer.