Malnutrition in cancer patients is one of the most influential factors in the evolution and mortality of such patients. To reduce the incidence of malnutrition, it is necessary to establish a correct nutritional intervention. For this purpose, precise tools and indicators must be developed to determine the patient’s condition. The main objective of this systematic review and meta-analysis was to analyze the relationship between different nutritional strategies, phase angle (PA), and handgrip strength in patients with cancer, with the secondary objectives being the modification of other indicators of nutritional status, such as weight and body mass index (BMI). A systematic review of randomized clinical trials was carried out in March 2023 in the databases PubMed, Web of Science, Cochrane, and Scopus. As a risk-of-bias tool, RoB 2.0 was utilized. A total of 8 studies with a total of 606 participants were included in the analysis. A significant increase in PA was observed after the different nutritional strategies (SMD: 0.43; 95% CI: 0.10 to 0.77; p = 0.01; I2 = 65.63%), also detecting a significant increase in handgrip strength (SMD: 0.27, 95% CI: 0.08 to 0.47; p = 0.01; I2 = 30.70%). A significant increase in PA and handgrip were observed in cancer patients subjected to different nutritional strategies. These results suggest that these indicators could be used in the nutritional and functional assessment of the patients.