It can be said that it is normal for lung cancer patients to lose weight for a period of time, which is the result of disease and psychological effects. As a doctor, we should first analyze the causes of patients' weight loss and find ways to reduce it. As a family member, we should mix nutrition according to the patient's dietary preferences, focusing on high-protein, high-calorie and digestible foods, with a small amount of meals. As patients, we should exercise moderately. Abdominal massage can promote gastrointestinal peristalsis and increase appetite. In addition, ensure adequate sleep. For patients with persistent diarrhea, medication should be given, and the diet structure should be adjusted, with a low-fiber and low-fat diet as the mainstay.