How can I gain weight during chemo?

Eat on a schedule, with 5 or 6 small meals a day about every 2 to 3 hours. Add protein and calories to foods you can manage, such as cheese, whole milk, peanut butter, eggs and avocado, and use shakes or soups on days solid food is hard. Ask your team for a referral to a registered dietitian.

Is it normal to lose weight during chemotherapy?

Appetite loss and weight loss are common side effects of cancer and its treatment. Common does not mean it should be ignored: NCI advises reporting weight loss of more than 3 to 5 pounds in one week to your doctor.

Is weight gain during chemo a good sign?

Not necessarily. NCI explains that some people gain weight during treatment, more often with breast, ovarian or prostate cancer, from causes such as fluid retention, steroids or hormone therapy. Let your doctor know about any gain so they can check the cause, and tell them right away if it is sudden.

What are good high-calorie foods for cancer patients?

Foods on NCI's lists include cheese, whole milk, yogurt, eggs, peanut butter and other nut butters, nuts and seeds, avocado, beans and lentils, tofu, meat and fish. Adding olive oil or nut butter to foods raises calories without making portions bigger.

Can I use protein powder during chemo?

NCI suggests adding unflavored protein powder to foods such as macaroni and cheese, oatmeal, sauces, mashed potatoes, smoothies and soups. Check with your dietitian first.

Why can't I gain weight after chemo?

Some eating problems, including weight loss and taste changes, can last after treatment ends, and cancer cachexia can cause weight and muscle loss even when you are eating well. Talk with your doctor and a registered dietitian, who can look for the cause and adjust your plan.

How to Gain Weight During Chemo

By Mustafa Bilgic · Updated September 2026 · Based on National Cancer Institute patient guidance and USDA FoodData Central.

Losing weight during chemotherapy is common, and it matters. The National Cancer Institute (NCI) warns that malnutrition can leave you weak, tired and less able to fight infection or even finish treatment. The goal during treatment is not a strict diet. It is getting enough calories and protein on good days and bad days. This page gathers the practical steps from NCI's patient guidance, plus a booster tool that adds up calories and protein from everyday foods.

Educational, not medical advice. Your oncology team and registered dietitian know your treatment, blood counts and any diet limits, so follow their advice first and tell them about weight loss early. If you are losing weight without a known reason and have not seen a doctor about it, make an appointment.

Key takeaways

Tell your care team about appetite or weight changes early. NCI says to report a loss of more than 3 to 5 pounds in one week.
Eat on a schedule: 5 or 6 small meals a day, about every 2 to 3 hours, instead of waiting to feel hungry.
Add protein and calories to foods you can manage: cheese, whole milk, nut butter, eggs, avocado and oils.
Handle food carefully, because some treatments make foodborne illness more likely.

Why chemo makes weight hard to keep on

NCI lists appetite loss and weight loss among the common side effects of cancer and its treatment. Anyone with cancer can lose weight, but it is more likely with head and neck, lung, pancreatic or liver cancer, or cancer in the upper digestive system. Chemotherapy drugs can also harm fast-growing healthy cells, such as those lining the mouth and digestive tract, which is one reason eating gets harder during treatment.

The side effects that get in the way of eating include nausea and vomiting, diarrhea, constipation, feeling full quickly, painful swallowing, mouth sores, dry mouth and taste changes. Anxiety, pain, depression and fatigue can take away appetite too.

This is why cancer nutrition advice can look upside down. NCI notes that people with cancer often need diets that are different from what we think of as healthy, with extra protein and calories, which may mean more meat, fish, eggs, dairy, fats and plant proteins than someone without cancer would eat. One more term to know: cancer cachexia, a wasting syndrome with weakness and loss of fat and muscle. NCI says it can happen even when you are eating well, and it is treated differently from ordinary weight loss.

Eat by the clock, not by hunger

NCI's tips on when to eat, from its Eating Hints booklet and its guidance on appetite loss:

Eat on a schedule rather than waiting until you feel hungry.
Have 5 or 6 small meals a day, about every 2 to 3 hours, instead of 3 large ones. Set an alarm, or use TV commercial breaks as a reminder.
Eat within 1 hour of waking up, and eat the high-protein part of a meal first, while appetite is strongest.
Sip only small amounts during meals so there is room for food, and drink between meals instead.
Have a bedtime snack.
Make the most of good days. Eat a bigger meal when you feel your best, and use liquid meals when appetite is low.

On hard days, NCI says it is fine to eat the same foods again and again if they are the ones that sound good. Do not worry if you cannot eat at all on some days, but tell your doctor if you cannot eat for more than 2 days.

Add calories and protein to what you already eat

NCI calls this power-packing: adding protein and calories to other foods, with toppings like peanut butter, olive oil, nuts, seeds and avocado. The booster below adds up what small additions are worth. Tap + for each serving you could manage in a day. The foods follow NCI's lists of ways to add protein and calories, and the values come from USDA FoodData Central.

Calorie and protein booster

Servings per day. Totals update as you tap.

Added calories a day

0 g

Added protein a day

Values: USDA FoodData Central, SR Legacy (per 100 g, scaled to each portion). Your dietitian can set a calorie and protein goal that fits your treatment. Almonds are dry roasted, in line with NCI's advice to eat shelled, roasted nuts during treatment.

Easy ways to power-pack meals

These ideas come from NCI's lists of ways to add protein and calories:

Cheese: melt it on eggs, vegetables and potatoes, or grate it into soups, sauces and mashed potatoes.
Milk: use whole milk instead of low-fat, and milk instead of water in hot cereal, soups and cocoa.
Dry milk or protein powder: stir nonfat instant dry milk or unflavored protein powder into milk drinks, mashed potatoes, sauces, soups and oatmeal.
Nut butters: spread peanut butter on toast, crackers and fruit slices, or blend it into shakes.
Eggs: add chopped hard-boiled eggs to salads and vegetables.
Beans, lentils and tofu: add them to soups, pasta, salads and casseroles.
Avocado: spread it on toast, add it to sandwiches or blend it into smoothies.
Meat and fish: add chopped, cooked leftovers to eggs, soups, salads and pasta.

Drinks when solid food is hard

When chewing or swallowing is tough, liquids can carry a lot of nutrition. NCI suggests milkshakes, smoothies, juices or soups on days you do not feel like solid food, made with whole milk or yogurt to raise the calories. Nutrition supplement drinks sipped between meals are another option, and NCI suggests asking your dietitian which high-calorie, high-protein drinks suit you.

Drink plenty overall, especially on days you cannot eat much. Eating Hints says most adults should drink 8 to 12 cups of liquid a day, unless your care team tells you otherwise.

Handle food safely during treatment

NCI explains that chemotherapy can lower the number of white blood cells, which fight infection, so you may be at higher risk of illness from food. These are NCI's food safety steps for people whose treatment makes them prone to foodborne illness. Ask your team which ones apply to you, and for how long.

Do

Keep hot foods hot and cold foods cold, and refrigerate leftovers as soon as you finish eating.
Scrub raw fruits and vegetables with a brush and water, including melons, oranges and avocados before cutting.
Use one cutting board for meat and another for produce, and wash hands, knives and counters.
Cook meat, poultry and eggs thoroughly: eggs hard, not runny, and no pink inside meat.
Choose pasteurized juices, egg products and milk products.
Eat shelled, roasted nuts, and only freshly cooked rice.

Avoid

Raw fish or shellfish, such as sushi and uncooked oysters.
Produce that is hard to scrub, such as berries and grapes.
Raw nuts, foods from bulk bins, and buffets, salad bars or self-service counters.
Moldy cheeses such as blue cheese and Roquefort, and food past its freshness date.
Perishable food left at room temperature for more than 2 hours.

Side effects that get in the way

Feeling full quickly: NCI suggests smaller meals and snacks five to six times a day, and drinking most fluids between meals rather than during them.
Mouth sores: NCI suggests drinking through a straw to move liquid past the painful parts of the mouth.
Aftertaste or a bad taste: brushing your teeth and rinsing your mouth can relieve symptoms and aftertaste.
Nausea and vomiting: tell your team. NCI notes that there are medicines that often prevent or relieve nausea and vomiting before they become a problem.
Low energy: a short walk or other light activity may help your appetite, and NCI says many people with cancer feel better when they exercise each day.

For more general tips on eating more when appetite is low, see our guides to increasing your appetite and gaining weight with a small appetite. Check any tip against your team's advice during treatment.

When to call your care team

Weight loss: NCI says to report a loss of more than 3 to 5 pounds in one week to your doctor, and to speak with your doctor or dietitian right away if you start to lose weight.
Not eating: tell your doctor if you cannot eat for more than 2 days.
Appetite that will not come back: ask your doctor about appetite stimulants, medicines that can increase appetite.
Sudden weight gain: some people gain weight during treatment, from fluid, steroids or hormone therapy. NCI says to tell your doctor right away if the gain is sudden, such as 5 pounds in a week, or does not stop.
Ongoing trouble eating: if you keep losing weight, your doctor or dietitian may suggest tube feeding or IV nutrition to support you.

Regaining weight after treatment ends

NCI says many eating problems get better once treatment is over, but some, including weight loss and changes in taste or smell, can last longer than treatment. After head and neck cancer, or surgery on the stomach or intestines, eating problems may be long-term. NCI's booklet notes that healthy eating cannot by itself keep cancer from coming back, but it can help you regain strength, rebuild tissue and feel better.

Simple steps from NCI for this stage: prepare easy meals you like, cook 2 or 3 meals at a time and freeze extras, and eat a wide variety of foods. A registered dietitian can still help after treatment, whether you need to rebuild weight or manage lasting eating problems. Our guide to gaining weight after illness covers gentle, general recovery steps.

For caregivers

NCI's advice for family and friends: do not be surprised or upset if food preferences change from day to day, and offer gentle support rather than pushing your loved one to eat. Help with meal planning, shopping, cooking and cleaning, keep a list of foods they like, and ask the doctor for a referral to a dietitian so you can meet together.

Educational, not medical advice. This guide is general information based on public NCI guidance. It is not a substitute for advice from your oncology team or registered dietitian, who can tailor calorie, protein and food safety advice to your treatment. Report weight loss or eating problems to your care team. Operator: Mustafa Bilgic.

Frequently asked questions

How can I gain weight during chemo?: Eat on a schedule, with 5 or 6 small meals a day about every 2 to 3 hours. Add protein and calories to foods you can manage, such as cheese, whole milk, peanut butter, eggs and avocado, and use shakes or soups on days solid food is hard. Ask your team for a referral to a registered dietitian.
Is it normal to lose weight during chemotherapy?: Appetite loss and weight loss are common side effects of cancer and its treatment. Common does not mean it should be ignored: NCI advises reporting weight loss of more than 3 to 5 pounds in one week to your doctor.
Is weight gain during chemo a good sign?: Not necessarily. NCI explains that some people gain weight during treatment, more often with breast, ovarian or prostate cancer, from causes such as fluid retention, steroids or hormone therapy. Let your doctor know about any gain so they can check the cause, and tell them right away if it is sudden.
What are good high-calorie foods for cancer patients?: Foods on NCI's lists include cheese, whole milk, yogurt, eggs, peanut butter and other nut butters, nuts and seeds, avocado, beans and lentils, tofu, meat and fish. Adding olive oil or nut butter to foods raises calories without making portions bigger.
Can I use protein powder during chemo?: NCI suggests adding unflavored protein powder to foods such as macaroni and cheese, oatmeal, sauces, mashed potatoes, smoothies and soups. Check with your dietitian first.
Why can't I gain weight after chemo?: Some eating problems, including weight loss and taste changes, can last after treatment ends, and cancer cachexia can cause weight and muscle loss even when you are eating well. Talk with your doctor and a registered dietitian, who can look for the cause and adjust your plan.

Keep reading

References

Sources: NCI: Weight Changes, Malnutrition, and Cancer · NCI: Nutrition in Cancer Care (PDQ), Patient Version · NCI: Eating Hints, Before, during, and after Cancer Treatment · USDA FoodData Central.