Objective: Anthropometric measurements including body mass index (BMI), mid-upper arm circumference (MUAC), and calf circumference (CC) are simple and convenient indicators of nutritional status and muscle mass. However, most of their reference values come from studies based on healthy Western populations. The optimal reference values of these anthropometric factors in Asian patients with cancer are unclear. The aim of this study was to develop reference values of severely and moderately low BMI, MUAC, and CC by analyzing a large sample of patients with cancer from a nationwide population. Methods: We conducted a retrospective analysis of 16 104 patients who were diagnosed with malignant diseases from June 2012 to January 2019. The median age of the patients was 58 y, and 52.5% were men. Optimal stratification was used to calculate reference values using X-tile software. Kaplan-Meier and multivariate Cox analysis were performed to analyze survival data. A receiver operating characteristic analysis was conducted to test the performance of new reference values in diagnosing malnutrition. Results: The optimal reference values were calculated for BMI (moderately low: 19.7 [women] and 19 [men]; severely low: 16.7 [women] and 16.7 [men]), MUAC (moderately low: 24.5 [women] and 23.2 [men] severely low: 20.6 [women] and 19.4 [mnen]), and CC (moderately low: 29.1 [women] and 29.3 [men]; severely low: 26.7 [women] and 26.9 [men]). New reference values had more significant affects on mortality risk and better performance in predicting malnutrition than existing ones. Conclusions: The present study defined reference values of moderately and severely low BMI, MUAC, and CC, which showed strong associations with quality of life, malnutrition, and mortality risk. New reference values from the present study are classification references specifically for the Asian population, which is a new step to promote the application of Global Leadership Initiative on Malnutrition criteria and its severity grading system in Asia. (c) 2022 Elsevier Inc. All rights reserved.