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Tips for diet problems

Advice on dealing with diet problems such as loss of appetite, taste changes, mouth problems, diarrhoea and constipation.

Loss of appetite

Cancer treatment may cause weight loss and loss of appetite. There are a number of ways of dealing with this.

If you find you have a loss of appetite, some of the following suggestions might help.

  • Avoid filling your stomach with a large amount of liquid before eating - drink after your meal.
  • Try to eat small amounts of high protein and calorie foods every 2 or 3 hours instead of 3 large meals a day. High protein foods include meat, fish, eggs, dairy foods, beans and pulses.
  • Ask friends and relatives to help prepare meals for you - cooking your own food can sometimes put you off eating.
  • Add extra calories and protein to any food that you eat (using butter, milk, cream, sugar, honey and cheese).
  • Choose foods that appeal to your sense of smell and eat cold or slightly warm food if the smell of cooking puts you off eating.
  • Prepare and store small servings of your favourite foods ahead of time, so there is always something to eat when you feel hungry.
  • Have a stock of convenience foods in the cupboard, such as tinned soups and puddings.
  • Eat puddings and desserts - foods with fat or sugar are good sources of calories.
  • Don't be afraid to try out new foods and tastes - you may be surprised at what you like.
  • Chew food well and eat slowly.
  • With your doctor's permission, small amounts of your favourite alcoholic drink might boost your appetite.
  • Avoid getting over tired - you will find everything more difficult to cope with if you are exhausted.
  • Don't give yourself a hard time if you really don't feel like eating for a few days after treatment - it is important to drink, but you can make up for lost calories between treatments.

If you are worried about losing weight, ask your doctor about high calorie 'meals in a drink'.

You may also have a poor appetite because you feel sick.

Taste changes

Food and drink can taste peculiar when you are having some chemotherapy drugs. Radiotherapy to the mouth may have a permanent effect on your sense of taste. This may improve slowly over time. 

If you have had any treatment that affects your sense of smell, this will affect your sense of taste. Many of us don't realise, but the scent of food contributes a great deal to how it tastes.

  • Avoid foods that taste strange to you, but try them again every few weeks as your taste may have gone back to normal.
  • Choose foods that have strong flavours (eg herbs, spices and marinades) if all your food tastes the same. Try adding garlic, lemon juice, herbs and spices.
  • Marinate foods overnight or for a few hours (even 10 minutes will make a difference). Make a marinade with a couple of tablespoons of olive oil, and whichever herbs or spices you fancy. Add a splash of wine or some lemon juice if you like.
  • Or you could use a dry marinade – sometimes called a rub. Mix up spices and herbs and slap onto uncooked meat or fish with clean hands.
  • Avoid hot (spicy) foods if you have a sore or infected mouth.
  • Gravies and bottled sauces can help to add flavour to a meal.
  • You might find you prefer stronger versions of your favourite foods such as smoked ham or bacon or strongly flavoured cheese.
  • You may prefer to avoid your favourite foods and drinks altogether during chemotherapy so there is no danger of going off them for good. This is particularly useful for children.
  • If food tastes metallic use plastic utensils.
  • Avoid very cold or hot foods.
  • Use chutney, pickle or relish to add flavour to food.
  • Keep your mouth clean and brush your teeth well.


Diarrhoea is a common side effect of some cancer treatments. It often disappears after a few days, but it may go on for some weeks after your treatment. It's not only unpleasant, but can also make you feel weak and tired. And if it is severe it may lead to weight loss.

It is easy to become dehydrated if you have bad diarrhoea, so try to drink plenty of fluids. If you can't drink enough, or think you are losing more fluid in diarrhoea than you can replace by drinking, you must see your doctor.  

If you have diarrhoea after any treatments, tell your doctor or nurse. They can give you tablets to take with your next lot of treatment to reduce the diarrhoea. You can also ask about soothing creams to apply around your anus. Severe diarrhoea can make the skin in this area get very sore and sometimes break down. 

  • Eat smaller meals and more snacks.
  • Avoid high fibre foods such as beans, broccoli, cabbage, cauliflower and fruit. Also cereals such as weetabix and bran flakes, brown bread and rice. Ask the dietitian at the hospital for advice if you're not sure what to eat.
  • Try low fibre, starchy foods such as white bread and rice, pasta, and potatoes without their skins.
  • Drink plenty of fluids to prevent dehydration.
  • Ask your doctor to prescribe anti diarrhoea drugs.


Some drugs can cause constipation, particularly painkillers, but also some chemotherapy drugs. Constipation can make you feel full and not want to eat.

Your doctor or nurse should give you mild laxatives to take while you are having any treatments that can cause constipation. If you are constipated for more than 3 days, it is important to tell your doctor.

Constipation is easier to sort out if it is treated early. It may also help to drink plenty of fluids and eat as much fresh fruit and vegetables as you can. If you can't manage the food, don't worry too much, but make sure you do drink.

  • Drink 8 to 10 cups of fluid each day if possible - water, prune juice and orange juice can all help.
  • Eat high fibre foods such as fruit, vegetables, lentils, beans and wholegrains (unless you have a blockage in your bowel).
  • Do some exercise each day, even if it is just a short walk.

If you have changes in your bowel habits that carry on for more than a few days, let your doctor know straight away.

Mouth problems

If you have a sore mouth and throat you might find it hard to swallow. So a soft diet might be best until it gets better. 

You may find cool drinks soothing if you have a sore mouth. Avoid hot (spicy) or sharp foods that may sting your mouth.

Last reviewed: 
04 Jan 2017
  • Cancer and its management (7th edition)
    Tobias J and Hochhauser D
    Wiley-Blackwell, 2015

  • Nutrition and Cancer
    Edited by Clare Shaw
    Wiley-Blackwell, 2011

  • National Institute for Health and Care Excellence (NICE) guidance
    Quality standard for nutrition support in adults (QS24) – November 2012

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