Purpose: Preoperative malnutrition in gastric cancer patients is known to be one of the risk factors of postoperative complications. During the preoperative investigation period gastric cancer patients have to skip meals several times due to examinations and this carries a risk of malnutrition. In the present study, the changes in preoperative nutritional status in clinical stage I gastric cancer patients were examined and the relationship between the number of times of skipping meals and the degree of changes in their nutritional status was also analyzed. Materials and Methods: In clinical stage I gastric cancer patients who underwent laparoscopic gastrectomy at the Cancer Institute Hospital in the period from January 1st to September 30th 2014, nutritional markers were compared between the first visit to the hospital and the day before surgery. The relationship between the changes in the nutritional markers and the number of skipping meals per day were also investigated. Results: A total of 175 patients were eligible. Median duration between the first visit to the hospital and the day before surgery was 26 (9–104) days and median number of skipped meals was 4 (1–8). Average serum albumin on the day before surgery was 4.16 g/dl, which was significantly lower than that at the time of the first visit to the hospital; 4.34 g/dl (P< 0.001). The change in serum prealbumin from the first hospital visit to the day before surgery was −9.47 (−29.52 – +6.12)% in the patients who skipped meals 0.24 times per day or more, which was significantly larger than that in the patients who skipped meals less than 0.24 times per day; −3.02 (−35.87 – +47.5)% (P=0.003). Conclusion: Skipping meals due to preoperative examinations can cause malnutrition in gastric cancer patients. Skipping meals should be avoided as much as possible and intake of dietary supplement products without disturbing the examinations should be considered.