Weight gain after chemotherapy for lung adenocarcinoma is normal if it is caused by improved appetite; it is not normal if it is caused by sodium retention. If weight gain occurs after chemotherapy, it is necessary to clarify what causes the weight gain. 1. Improvement of appetite: After chemotherapy, the consumption of the tumor on the body is reduced, the patient’s appetite may improve, eating more, and at this time, weight gain may occur, which is a normal phenomenon. 2. Sodium retention: chemotherapeutic drugs may damage the liver and kidney function, which may cause sodium retention and lead to weight gain, this phenomenon is an abnormal situation, we should consult the doctor in time, and under the doctor’s guidance, we can use diuretic drugs to reduce sodium retention, such as furosemide and so on. It is recommended that patients should consult a doctor if they feel unwell, and take active treatment under the doctor’s guidance.