To develop customized food products for gastric cancer patients, it is crucial to understand their dietary characteristics and changes in their perception of smell and taste due to their condition. This study conducted in-depth interviews and administered olfactory and gustatory tests on 20 patients with gastric cancer. A control group of 20 healthy, gender and age matched individuals, was included for comparison. Patients reported difficulties in sustaining their appetite, particularly during chemotherapy. This could be attributed to gastrointestinal discomfort and an altered perception of smell and taste. The olfactory test revealed that cancer patients were significantly less sensitive than the control group. Also, a smaller number of participants in the cancer group were reported to have a normal taste function, which enabled them to perceive umami, one of the five basic taste compared to those in the control group. These findings demonstrated that gastric cancer patients experience post-surgical digestive issues, chemotherapy-induced changes in smell and taste, and appetite loss. To improve the quality of life of these patients and the efficacy of the treatment, it is necessary to consider not only their nutritional requirements but also other factors such as appetite loss and discomfort when developing meals specifically for them.