Your community

Cancer, nutrition, and weight gain

By Lucy Eldridge, Head of Dietetics at the Royal Marsden Hospital

Lucy Eldridge

So much goes on when you are diagnosed with cancer. Once some of the dust finally settles, and you get into a bit of a rhythm with treatment and appointments, you might wonder about what changes you might want, or need, to make to your lifestyle.

Good nutrition is really important for everyone, but especially if your body is going through cancer and treatment. In this article, Lucy Eldridge – a registered dietitian, and Head of Dietetics at the Royal Marsden Hospital in the United Kingdom – provides some top tips for people who might be struggling with nutrition and weight after a cancer diagnosis.

Why am I gaining weight when I have cancer?

Most people who have cancer or who are undergoing treatment for cancer find it hard to gain weight, so gaining it is relatively unusual – but it can happen.

Slight fluctuations aren’t something that you should worry about,1,2 and can be caused by a number of factors, including:

  • A change in lifestyle. For example, you may become less active, or stop work or struggle with fatigue (which can be cause by cancer itself, and sometimes treatment)1,2
  • Certain treatments. For example, medicines like steroids can cause you to gain weight more easily1
  • Fluids from your treatment. For example, if you receive medicine from a bag of liquid via a tube in your arm (an intravenous drip) then the liquid will temporarily add to your weight1

If you do find that you are suddenly gaining weight very rapidly, you should tell your medical team.1 They can find out what is causing it and make any adjustments to help you manage it.

If my weight gain is related to reduced exercise, or not being able to move as well as other people, what are some steps I can take to manage this?

Trying to maintain exercise during treatment is important: exercise can help you maintain lean muscle mass, which has been shown to be beneficial.3,4

Exercise can be kept as simple as walking. If you don’t want to walk alone, many primary care and charities organise groups for people to get together and exercise.

If you don’t feel up to getting out of the house, there are simple exercises you can do at home. ‘Get Active, Feel Good’ is a great resource available from UK charity Macmillan Cancer Care, which is full of tips and advice for how you can get active with cancer:

How can I manage weight gain if I have cancer?

Ultimately, making sure your body is getting a good amount of nutritious food at this time is really important. Often, weight gain is caused by reduced activity so finding ways to increase this might be helpful – speak to your medical team and they can give you advice of ways to get more active.

There are also some practical tips you can follow too, when it comes to food and drink:

  • Be mindful of what you are eating during mealtimes – a balanced approach to a diet is essential, and it’s particularly important to be mindful of portions and cooking methods
  • Try keeping a food diary – there are a number of apps that you can use which will automatically calculate the number of calories and nutrients you are getting, or you could do it manually in a journal
  • Look for online tools that can help you understand more about what a heathy portion size is – you might be surprised by what some portion sizes actually are! The Association of British Dieticians (BDA) has some helpful information:
  • Set yourself small targets – for example if you want to eventually lose 10 kilos, break that into smaller targets of perhaps 2 kilos at a time
  • Making smart food swaps can be helpful – especially when it comes to finding healthy snacks. Why not try:
    • Fruit and vegetables, adding yogurt or humus for extra flavour
    • Plain scone
    • Small bowl of cereal with semi-skimmed milk
    • Rice cakes
    • Small handful nuts
    • Boiled egg
  • Make heathy choices when it comes to drinks, and avoid sugary beverages or alcohol

I’ve been told I need to take my medicines with food – how should I manage my diet and weight around this?

If you need to eat specific amounts of nutrition with your medication, then it is essential that you plan this into your day. Remember to choose nutritious options and not empty calories.

During the rest of the day, it is then important to eat mindfully – choose foods like fruits and vegetables that are filling, but not high in refined sugars.

My weight gain is affecting my self-esteem… what can I do?

There may be times when changes to your body can make you self-conscious or affect how you feel about your body. These feelings could be caused by weight, scarring from surgery, hair loss… everyone is different.

Ultimately, as you go through treatment the most important thing is your health, so making time to eat nutritious foods and look after yourself are important. Your mental health also needs taking care of at this time, so if you feel badly affected then speak to your medical team and they can help you find the support you need.

Are there any recipes that are good for people with cancer?

When it comes to cooking for somebody who has cancer, there are lots of really useful books and resources available! Many charities will have information and recipes available online. For example, why not have a look at:

  • The World Cancer Research Fund
    This charity has made a range of healthy cookbooks that can be used for all the family. They are designed around producing meals that have less fat, sugar and salt, so they are especially useful for people who are eating well and wish to maintain or lose weight
  •  UK charity Macmillan Cancer Care have recipes that are specifically designed for those with cancer. They are also organised by symptoms of cancer or side effects of treatment that you may experience, which means you can find recipes that are specifically good for you
  • If you are interested in buying a cookbook, why not have a look at The Royal Marsden Cancer Cookbook (ISBN-10: 0857832328)? This contains recipes for those who are having treatment, or who have completed treatment, and can be shared with family and friends. Additionally, it also shows you which recipes are better if you are experiencing certain symptoms of cancer, or side effects 

What is an important piece of food advice I might find surprising?

Most people don’t realise how important protein is! Protein is essential in the diet – especially for people receiving cancer treatment as it helps maintain lean body mass.4 It’s especially helpful for recovery after surgery.5

Lean proteins you could try and include in your diet include:5

  • Lean meats such as chicken, fish, or turkey
  • Lean red meat (no more than 500g per week)
  • Low-fat dairy products such as milk, yogurt, and cheese or dairy substitutes
  • Eggs
  • Nuts and nut butters
  • Beans & pulses
  • Soya

How can my friends and family who are helping me get involved with food and mealtimes?

When it comes to food, even a little help can make a big difference to somebody with cancer. A carer could:

  • Offer to join in with cooking meals, or prepare you a big batch of something if you aren’t feeling up to cooking yourself
  • Sit and eat with you, and make mealtimes more sociable and enjoyable
  • Go to the supermarket for you, and pick up ingredients if getting out isn’t so easy for you

What about if I go on holiday, or want to go out for a meal with friends and family… what should I do?

Some cancer treatments can affect your immunity (your doctor might describe it as having a weakened immune system, or being immunocompromised). In these cases, food safety is really important.

Eating at reputable establishments is the best way to make sure the food you are served is clean and has been prepared carefully. In some countries like the UK, restaurants are obliged to publish their food hygiene ratings, and these are also available online.

Water cleanliness:6

  • Check guidance when it comes to drinking water abroad – water in some countries isn’t sanitised to the same extent as you might be used to
  • In these cases, use bottled or boiled water – even to clean your teeth
  • When you buy bottled water, always check the bottle seal is intact
  • Don’t forget that ice in drinks may also be made from contaminated water, so you may want to ask for drinks with no ice
  • If you are concerned about water quality, you should also avoid eating salads, and raw fruits and vegetables unless you are sure they have been washed in sanitised water. Fruits that can be peeled (so you can access flesh that hasn’t come into contact with the water) are fine
  • You can buy special water filters for travelling which might be useful to have as a backup

Ingredients to be careful of:

Both at home and when out and about, certain ingredients should be avoided, as they are not pasteurised, or otherwise properly treated to kill any bacteria, moulds, or parasites that may be in them. These can include:2

  • Unpasteurised dairy products, including mould ripened or blue-veined cheese
  • Raw or runny eggs
  • Sushi
  • Pâté
  • Reheated rice

  1. Cancer.Net. Weight Gain. 2019. Available from: Accessed May 2020.
  2. Guy’s and St Thomas’. Dietary advice during chemotherapy. 2018. Available from: Accessed May 2020.
  3. Pin F et al. Curr Opin Support Palliat Care 2018; 12(4): 420–426.
  4. Tsai S. Nutr Clin Pract 2012; 27(5): 593–598.
  5. American Cancer Society. Nutrition for the Person With Cancer During treatment. 2018. Available from: Accessed May 2020.
  6. National Health Service. Food and water abroad. 2019. Available from: Accessed May 2020.