Poor appetite and weight loss during brain tumour treatment

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Read about why poor appetite and weight loss may occur during brain tumour treatment and what you can do to help your child.

Key points

  • A brain tumour and its treatment can affect a child’s appetite, which may cause weight loss, fatigue and nutrient deficiencies.
  • Side effects of treatment that can affect oral intake include loss of appetite, feeling full, fatigue, nausea and vomiting, sore mouth or throat, and diarrhea.
  • A high calorie and high protein diet may be needed if your child loses weight.

Brain tumours and their treatments can affect a child’s desire to eat. Not eating enough calories and protein can lead to weight loss, fatigue. A limited diet can sometimes lead to nutrient deficiencies. Nutrition is important during treatment as it will help your child withstand the effects of treatment, fight infections, and maintain their muscle strength and growth. Treatment side-effects such as tiredness, nausea and vomiting can make it difficult for your child to eat and may cause unwanted weight loss. Listed below are some common side effects your child may experience as well as suggestions on how to cope with these issues.

Which side effects of treatment may affect your child’s diet?

The following side effects of brain tumour treatment may affect your child’s diet:

  • Loss of appetite
  • Feeling full all the time
  • Fatigue
  • Nausea and vomiting
  • Sore mouth or throat
  • Diarrhea
  • Constipation

How can these side effects be managed?

Loss of appetite

  • Serve smaller portions as they will appear less overwhelming.
  • Allow your child to choose the meal or snack foods.
  • Change the focus by using special plates, cups or having an indoor picnic.

Feelings of fullness

  • Separate fluids and solid foods at the same mealtime.
  • Have 5 mini meals instead of 3 big meals each day.
  • Increase exercise and activity as much as possible.


  • Try to have protein foods every day such as meat, chicken, fish, eggs, beans, lentils, or tofu to build back strength.
  • Stay hydrated; being dehydrated can add to the fatigue.
  • Sometimes a liquid diet that is high in calories and protein is easier than trying to eat a full meal when you are tired. Try using a nutritional supplement, homemade smoothie or milkshake.

Nausea and vomiting

  • Sip fluids throughout the day; try water, fruit juices, popsicles , sports drinks, lemonade, iced tea, milk, ginger ale or other clear soft drinks.
  • Nibble on dry foods like crackers, dry cereal, bread, toast.
  • Try foods that won't produce a lot of cooking smells like cereal & milk, cold sandwiches, pasta with butter, toast with peanut butter, milk & plain cookie/cake, cheese & crackers, yogurt & fruit.
  • Some foods, such as meats or chicken, may be easier to keep down if they are served cold.

Sore mouth or throat

  • Choose soft meals like scrambled eggs, pancakes, soups, macaroni & cheese, crustless bread with nut butter or cheese spread, mashed potatoes.
  • Try easy to swallow snacks like ice cream, yogurt, cheesecake, canned fruit, pudding.


  • Drink plenty of caffeine-free fluids like water, sports drinks, diluted juices, and soups/broth.
  • Limit intake of greasy, spicy, or fried foods as this may make diarrhea worse.
  • Choose foods that will add bulk to the stool like bread, rice, bananas, potatoes, pasta, oatmeal or other cereals, crackers, and pretzels.

What to do when weight loss occurs

When weight loss does occur, your child may need to boost the calories and protein in the food they are currently eating. The goal of energy boosting is to increase the calories in the food they are normally eating and drinking without dramatically changing the amount of food they eat.

Energy boosting tips

High-energy ideas for children and teenagers

  • Serve whole (homogenized) or chocolate milk.
  • Try hot chocolate made with whole milk and topped with whipped cream.
  • Offer 3 meals and 2 or 3 snacks each day. Avoid grazing.
  • Avoid giving tea and coffee, since they have no calories.

For children and teenagers, use any of the following added to foods:

  • Butter and margarine: add to soup, rice, noodles, cooked vegetables, potatoes, sauces.
  • Sour cream: add to soup, potatoes, vegetables, salad dressings and use as a dip for fruits or vegetables.
  • Whipped cream: use sweetened on desserts, pudding, fruits, pancakes, or waffles.
  • Yogurt (minimum 4% fat): add to fruit, desserts, use on cereal, waffles, pancakes.
  • Cheese (30% or higher milk fat): use on crackers, sandwiches, hamburgers, meats, fish. Grate and add to sauces, casseroles, rice, potatoes, noodles, vegetable dishes.
  • Peanut butter/nut butters: spread on sandwiches, muffins, crackers, waffles, pancakes, fruit slices. Blend with drinks, use with ice cream or yogurt.
  • Nuts (for children over four years old ): serve as snacks, add to ice cream, yogurt, pudding, pancakes, waffles.
  • Meat or fish: add small pieces to vegetables, salads, casseroles, soups, omelettes, or noodles.
  • Add avocados to toast or salads, or have with tortilla chips.
  • Ice cream on its own or made into a milkshake.

Meal ideas

  • Meat, cheese and fruit trays with crackers or baguette.
  • Cream soups.
  • Breakfast for dinner with pancakes and bacon, fruit and yogurt.
  • Pasta filled with cheese or macaroni and cheese with extra butter/cheese.
  • Baked or mashed potatoes with cheese, bacon and sour cream.
  • Scrambled eggs with cheese, vegetables and ham.
  • Croissant with meat, cheese and mayonnaise.

Nutritional supplements

If your child is not eating enough food to maintain their weight, the dietitian, nurse, or doctor may recommend using a nutritional supplement. Different flavours are available. Supplements provide extra protein and calories.

Using nutritional supplements with success

It can be difficult to get your child used to drinking a supplement. Some supplements are too sweet. Some are too thick. Your child may also get tired of the same thing all the time. Here are some suggestions to help:

  • Add whole (homogenized) milk to the supplement to make it less sweet.
  • Keep the supplements in the refrigerator. They taste better cold.
  • Add ice cream or sherbet to make the supplement taste like a milkshake.
  • Add fresh, canned, or frozen fruit such as strawberries, bananas, or peaches to the supplement.
  • Freeze the supplement in a small bowl or paper cup. Your child can eat it with a spoon like frozen yogurt.
  • Freeze the supplement in an ice cube tray. Your child can suck on the cubes.
Last updated: January 31st 2022