Many patients will ask about the dietary considerations during the consultation process. First of all, should tumor patients eat less? This may be related to the propaganda of many websites that claim to be “popular science”, and the so-called “starvation therapy” should not be believed. Tumor cells do not die of starvation so easily. On the contrary, tumor cells consume much more energy than normal cells, and their energy intake is also very fast. The PET we use for examination relies on this principle, using labeled glucose to examine the site of the tumor. Tumor cells tend to take nutrients from normal cells if the body cannot provide sufficient nutrients. Many patients with advanced tumors die not from the tumor itself, but from poor nutritional status, which is called “cachexia”. Therefore, it is very important for nutrition to keep up with the consumption of tumor, even if you eat and throw up, it is better than not eating, there is always something that will be absorbed. If you really have poor appetite, lose too much weight in a short period of time or cannot eat normally, you can ask your doctor to prescribe some auxiliary medicine to increase your appetite or take protein powder and other nutritional elements. Secondly, what can’t I eat? Many patients hear people say that many things can not be eaten, in short, there are a thousand and one things that say anything. Some say you can’t eat beef, eggs, chicken, or fish and shrimp. In fact, there is no “taboo” in Western medicine. If you look at Westerners who are having chemotherapy while eating fried chicken, beef and ice cream, you will know that there are not so many taboos. Some patients will experience nausea, vomiting and other gastrointestinal reactions during the course of radiotherapy, so eating foods that suit their tastes can boost their appetite. I often tell patients to eat whatever they like. Except for certain cases such as intestinal obstruction, huge gastric ulcers at risk of perforation and certain post-operative patients, diet must be in accordance with medical advice, but others can basically eat as normal, unless the doctor has special instructions. Of course, smoking and alcohol or quit it, there are a hundred harm but no benefit. We should also pay proper attention to what the ancestors called “fire”, and not to eat too much stimulating, such as fried or spicy food. Patients using certain chemotherapy drugs such as oxaliplatin should be careful to avoid cold foods during and for a few days after chemotherapy. Again, what should I eat? Foods rich in protein, vitamins, and starches are good. It is not necessary to spend too much to buy all kinds of supplements. Cordyceps, bird’s nest and shark’s fin do not bring much more nutrition than an egg. If some side effects occur during the treatment process, you can pay proper attention to the diet, such as severe mouth ulcers try to eat semi-liquid, liquid food and vitamin-rich food; anemia eat more iron and vitamin-rich food. In case of gastrointestinal reactions, you can adopt the method of eating less and more meals to try not to be hungry. Finally, do I need intravenous rehydration? Patients with severe vomiting, diarrhea or a significant decrease in food intake during post-operative patients or radiotherapy are necessary to have intravenous fluids to supplement nutrition. Other patients who are able to eat normally and have no significant weight loss and no dehydration such as diarrhea do not need intravenous rehydration. Patients who can usually take oral supplements can choose to take oral protein powder and other methods to replenish energy. It is also advisable to exercise, as moderate exercise can promote physical recovery and maintain a happy mood, which can help improve the efficacy of treatment. Oncologists in the United States often tell patients to do aerobic exercises such as swimming, running, cycling, playing tennis, etc. are all good exercises.