Eating during chemotherapy comes down to getting enough protein and calories to maintain your strength, while adapting what you eat to whatever side effects hit you hardest. Most people cycle through nausea, taste changes, mouth sores, and digestive issues at different points in treatment, so there’s no single perfect diet. Instead, you need a flexible approach and a toolkit of foods that work for each situation.
Protein and Calories: The Two Priorities
Chemotherapy breaks down cancer cells, but it also damages healthy tissue. Your body needs significantly more protein than usual to repair that damage. A healthy adult typically needs about 0.8 grams of protein per kilogram of body weight per day. During treatment, that requirement can jump to 1.5 grams per kilogram or higher. For a 150-pound person, that’s roughly 100 grams of protein daily, nearly double the normal amount.
Getting that much protein is difficult when your appetite has disappeared. Focus on calorie-dense, protein-rich foods that pack a lot of nutrition into small portions. Eggs, cottage cheese, nut butters, yogurt, and skinless chicken or tofu are all reliable options. When you can’t face a full meal, even a few spoonfuls of peanut butter on toast or a small smoothie with milk powder stirred in will help.
When You Have No Appetite
Loss of appetite is one of the most common problems during chemo, and fighting it with three big meals a day rarely works. Eating small amounts every two to three hours is more realistic. The goal is to make every bite count calorically.
A few strategies that help:
- Add fats freely. Put butter on potatoes, bread, rice, noodles, and vegetables. Drizzle olive oil on pasta and into soups. These additions can double the calorie content of a dish without increasing its volume.
- Use nut butters. Spread peanut or almond butter on toast, crackers, banana slices, or apple slices. You get both protein and healthy fats in a few bites.
- Stir in powdered milk. Adding dry milk powder or powdered creamer to hot cocoa, cream soups, mashed potatoes, sauces, or puddings boosts both calories and protein without changing the taste much.
- Snack on seeds. Sunflower seeds, pumpkin seeds, and ground flaxseeds add calories and nutrients to salads, yogurt, smoothies, and casseroles.
What to Eat When You’re Nauseated
Nausea tends to be worst in the first few days after an infusion. Low-fat, bland, and lightly salted foods are the easiest to tolerate. Greasy, fried, or heavily spiced foods often make things worse. Eating slowly and keeping portions small helps, because an empty stomach can actually intensify nausea.
Foods that tend to sit well include plain rice, mashed potatoes, dry crackers, toast, oatmeal, cold sandwiches, hard-boiled eggs, cottage cheese, applesauce, popsicles, and sherbet. Cold or room-temperature foods are generally easier to handle than hot meals, partly because they give off less odor. If the smell of cooking triggers your nausea, try having someone else prepare food, or stick to cold meals like sandwiches and salads.
Sip cool, clear liquids between meals rather than with them. Ginger tea and peppermint tea, served lukewarm or cold, can help settle your stomach. Carbonated drinks without caffeine, like ginger ale, are another option.
Dealing With Taste Changes
Many chemo drugs cause a persistent metallic or bitter taste that makes familiar foods taste wrong. This is temporary, but it can make eating feel pointless for weeks at a time.
Switching to plastic utensils often reduces the metallic sensation. If foods taste flat or dull, stronger flavors can help compensate: marinades, barbecue sauce, soy sauce, mustard, vinegar, herbs, garlic, sharp cheddar cheese, or bacon bits. Choose fresh or frozen fish over canned, since canned fish tends to amplify the metallic taste. Tart flavors like lemon or vinegar can cut through blandness, though you’ll want to avoid these if you also have mouth sores.
Eating With Mouth Sores
Mucositis, the inflammation and ulceration of the mouth lining, makes eating painful. The key is avoiding anything that irritates damaged tissue. That means skipping acidic foods like tomatoes, citrus, pineapple, and vinegar, along with spicy foods, hot sauce, and alcohol.
Soft, cool foods are your best options: soups, purées, smoothies, porridge, pudding, and yogurt. Eating food cold or at room temperature can actually numb the mouth slightly and reduce irritation. If chewing is too painful, a blender becomes your most useful kitchen tool. Nearly any meal can be blended into a smooth consistency that delivers the same nutrition without the pain.
Managing Diarrhea
Chemo-related diarrhea calls for a temporary shift in what kinds of fiber you eat. Insoluble fiber, found in fruit skins, seeds, whole grains, and raw vegetables, speeds things through your gut and can make diarrhea worse. Soluble fiber does the opposite: it absorbs water and slows digestion. Good sources include oatmeal, white rice, cooked carrots, bananas, beets, and applesauce.
While diarrhea is active, stick to grains with less than two grams of fiber per serving. White bread, plain pasta, flour tortillas, and cooked barley all fit. For fruits and vegetables, choose peeled options: potatoes, sweet potatoes, squash, peaches, pears, mangos, and avocados. Limit raw vegetables, cruciferous vegetables like broccoli and cauliflower, berries, citrus fruits, and anything with seeds or tough skins. Once the diarrhea resolves, slowly reintroduce higher-fiber foods.
Staying Hydrated
Chemotherapy is hard on your kidneys, and dehydration makes every side effect worse. General guidance from Memorial Sloan Kettering for patients on certain regimens is to drink 8 to 12 glasses (8 ounces each) of fluid daily in the week after treatment. Water is the obvious choice, but milk, diluted juices, caffeine-free sodas, and electrolyte drinks all count.
Limit caffeine to about one cup of coffee or tea per day, and avoid alcohol. If you’re drinking sweet beverages like juice, dilute them with water (half and half works well) to reduce the sugar load, since too much sugar can trigger or worsen diarrhea.
Foods and Supplements to Avoid
Grapefruit and related fruits, including pomelo, Seville oranges, and limes, can interfere with how your body processes certain chemo drugs. Compounds in these fruits alter liver enzymes that metabolize medications, which can either increase drug levels to toxic concentrations or reduce their effectiveness. Your oncology team will tell you if your specific regimen is affected, but it’s generally safest to skip grapefruit juice and whole grapefruit during treatment.
Antioxidant supplements are a bigger concern than most people realize. A study of breast cancer patients found that those who took antioxidant supplements (vitamins A, C, E, carotenoids, or CoQ10) both before and during chemotherapy were 41% more likely to have their cancer return and 40% more likely to die compared to those who didn’t supplement. The concern is that antioxidants may protect cancer cells from the very damage that chemo is designed to cause. Getting antioxidants from food, like fruits and vegetables, is fine and encouraged. Taking them in concentrated supplement form during treatment is not.
Herbal supplements carry similar risks. St. John’s wort and ginseng, among others, can interfere with the same liver enzymes that process chemo drugs, potentially causing dangerous interactions. The safest approach is to stop all supplements during treatment unless your oncologist specifically approves them.
Food Safety During Treatment
Chemotherapy suppresses your immune system, which means foodborne infections are a real risk. For years, cancer centers prescribed strict “neutropenic diets” that banned raw fruits, raw vegetables, and many fresh foods. Recent research has moved away from this approach. A 2025 study published in Frontiers in Nutrition found no evidence that strict dietary restrictions reduced infections, and noted that these diets imposed unnecessary financial burden on patients without meaningful clinical benefit.
What does matter is basic food safety: washing hands thoroughly before preparing food, cooking meat and eggs to proper temperatures, avoiding cross-contamination between raw and cooked foods, and refrigerating leftovers promptly. These practices protect you far more effectively than eliminating entire food groups. You don’t need to give up salads or fresh fruit, but you do need to wash produce carefully and avoid buffets or foods that have been sitting out at room temperature.