Introduction In 2019, The EWGSOP2 group made updates on the definition and diagnosis of sarcopenia. The aim of this study is to determine the possible risk factors for chemotherapy dose-limiting toxicity (DLT). Methods Newly diagnosed gastrointestinal (GI) cancer patients were included in this prospective observational study. Chemotherapy DLTs were recorded in patients receiving platinum-based therapy. The patients were divided into two groups according to the current sarcopenia criteria. Results 75 patients were included in the final analysis. Chemotherapy DLT occurred in 52% (n = 39) of all patients who received platinum-based chemotherapy. DLT rates were 78.9% and 42.9% in sarcopenic and non-sarcopenic patients, respectively (p = 0.007). According to the results of the multivariate analysis, the only sarcopenia was found as a statistically significant risk factor for DLT. Conclusion Assessment of sarcopenia evaluated with the current EWGSOP2 diagnostic criteria is useful in predicting chemotherapy DLT development in patients with a diagnosis of GI cancer. In the future, current EWGSOP2 recommendations should be considered while designing a study investigating the correlation between sarcopenia and chemotoxicity.