This study aimed to assess the concordance between different anthropometric indexes in the Global Leaders Initiated Malnutrition Standards (GLIM) and the Geriatric Risk Index (GNRI) for evaluating muscle mass, while also exploring performance-based criteria for GLIM muscle content suitable for elderly patients with intermediate and advanced tumors. A total of 312 patients admitted to Shanghai Tenth People’s Hospital between September 2022 and June 2023 were retrospectively included. Nutritional assessments were conducted using the GLIM framework, employing grip strength, upper arm circumference, and calf circumference as criteria for muscle content evaluation. The diagnostic value of these tools was compared against the GNRI as a reference standard. Among the participants, 127 (40.71%) were diagnosed as malnourished by GNRI, while the GLIM assessments yielded 138 (44.23%), 128 (41.03%), and 162 (51.92%) malnutrition diagnoses based on grip strength, calf circumference, and upper arm circumference, respectively. Both GNRI and GLIM-grip strength were significantly associated with complications and length of hospital stays. Notably, using GNRI as a reference, GLIM-grip strength demonstrated good consistency in diagnosing malnutrition (K value = 0.692, P < 0.001), with calf circumference having the highest diagnostic value. In conclusion, grip strength is a practical and effective performance-based criterion within the GLIM standards and has the potential to enhance malnutrition diagnosis in elderly patients with advanced malignancies, highlighting its relevance in nutritional science.