Objective This study aimed to assess the real-life nutritional status changes and gastrointestinal symptoms in patients with advanced non-small cell lung cancer (NSCLC) receiving chemotherapy.Methods A total of 104 patients with metastatic NSCLC receiving first-line chemotherapy were included in this study. Unintentional weight loss, body mass index (BMI) changes, and gastrointestinal symptoms were recorded and evaluated. Biochemical parameters [hemoglobin (Hb) and albumin levels] were compared before and after two chemotherapy cycles using SPSS software.Results Of these patients, 65.38％ (68/104) experienced unintentional weight loss, whereas 30.77％and 12.5％ presented with ≥ 5％ and ≥ 10％ degrees of weight loss, respectively, within 6 months before first-line chemotherapy was administered. Then, 48.08％ (50/104) of the patients experienced unintentional weight loss after two chemotherapy cycles. The mean body weight after chemotherapy was 61.47 ± 10.37 kg, which was significantly decreased relative to that before chemotherapy (P < 0.05). The mean BMI after chemotherapy was 22.66 ± 3.34 kg/m2, which was also significantly diminished with respect to that during the previous chemotherapy cycle (P< 0.05). The most common gastrointestinal symptoms reported among all the study patients were anorexia (80/104, 76.92％), nausea (53/104, 50.96％), constipation (49/104, 47.12％), vomiting (48/104, 46.15％), taste disorders (40/104, 38.46％), and early satiety (32/104, 30.77％). The mean Hb levels after chemotherapy were 117.06 ± 16.67 g/L, which were significantly lower than those before chemotherapy (132.73 ± 16.42 g/L) (P< 0.05). No significant difference was noted between the mean albumin levels before and after chemotherapy (38.29 ± 4.22 g/L vs 38.17 ± 4.54 g/L;P= 0.798).Conclusion Weight loss history, gastrointestinal symptoms, and Hb level decreases are determinant factors of nutritional status in patients with advanced NSCLC and must be included in the screening, evaluation, and treatment of lung carcinoma.