Breast cancer patients should eat a light, small and frequent diet during radiotherapy, while consuming more high-protein and high-fiber foods and avoiding greasy foods. Because breast cancer itself is related to high fat, especially for obese women, so avoid eating high-fat foods. During breast cancer radiotherapy, patients will experience nausea, vomiting and loss of appetite. If they eat too many fatty things or things that are too greasy, patients will have a feeling of nausea. Avoid spicy and stimulating foods because chemotherapy is used appropriately during breast cancer radiotherapy, and chemotherapy will also cause patients’ digestive tract reactions, so avoid spicy and stimulating foods to damage the gastric mucosa.