Background: This study was aimed at evaluating the food intake and nutritional status of patients who underwent gastrectomy for gastric cancer based on a large-scale gastric cancer cohort. Methods: An observational prospective cohort study for gastric cancer has been conducted since 2010. From the cohort data, we selected the data for patients who completed at least 2 days of 3-day diet diaries and who underwent subtotal gastrectomy (STG) or total gastrectomy (TG). As a control group, patients who underwent endoscopic submucosal dissection were also included. The collected diet data were converted to macro- and micronutrients using computerized software, and the nutrient intakes were compared. Results: Among 6,556 patients who participated in the cohort study from 2011 to 2016, 1,289 patients who completed at least 2 days of 3-day diet diaries were included in this study. During the postoperative 3-month period, body weight was significantly decreased in the and TG groups. However, there was no difference in nutrient intake among the 3 groups except vitamin D and calcium intake. Similar results were observed during the postoperative 12 months period. Conclusions: Postoperative body weight loss and anemia might originate from altered absorptive function and metabolic change after gastrectomy rather than decreased nutrient intake.