Purpose: Intake and output measurement methods are inconsistent in nursing practice. An evidence-based nursing case study was conducted to provide evidence on intake measurement methods and to ultimately promote nursing practice. Methods: The PICO format was used to generate a clinical question on intake measurement methods(fluid only vs. all types of food) and its associations between the differences in intake and output, and body weight changes. A literature search was conducted through both the national and international databases, and the selected articles were assessed using the Risk of Bias Assessment tool for Nonrandomized Study. The level of evidence was graded using the GRADE system. Results: In total, 1,223 articles were screened, and four articles were selected in this study. Studies have indicated that there are no significant differences between the two methods(fluid only vs. all types of food) on both intake and output differences and body weight changes. The risk of bias in the literature was generally low, except for the intervention measurement area. Conclusion: There is no evidence that there are significant differences in intake measurement methods in intake and output differences and body weight changes. We suggest a fluidonly intake measurement method to improve the accuracy and convenience of nursing practice(weak recommendation, moderate quality evidence).