What to Eat When You Are Losing Weight With Cancer

By Meredy Birdi, HCPC-registered Specialist Cancer Dietitian and Nutritional Therapist

Weight loss during cancer can feel worrying, particularly when you notice the numbers on the scales dropping without meaning them to. I want to reassure you that there are lots of things that can help.

There are practical ways to get more nourishment from what you're eating and help support your weight, muscle mass and strength.

 

Why Does Weight Loss Happen During Cancer?

It may be one thing, or several things happening at the same time. Some of the reasons include:

• Poor appetite or feeling full quickly: you may not feel like eating or find that you can only manage small amounts at a time.

• Treatment side effects: nausea, vomiting, diarrhoea, constipation, taste changes, a sore or dry mouth and swallowing difficulties can all make eating harder.

• Stress and anxiety: worry can have a very real effect on your appetite and eating.

• Fatigue: shopping, preparing meals and even eating itself feel like hard work.

• Changes to the way you eat: some people make quite significant changes to their diet after a cancer diagnosis. These may be very nourishing changes, but can sometimes result in weight loss.

• Fear around food choices: it's understandable to become more cautious about food after a cancer diagnosis, particularly when there is so much conflicting information. Sometimes this can lead to foods being cut out, making it harder to eat a varied, nourishing diet.

• Problems digesting or absorbing food: some cancers, surgery and treatments can affect how well you digest or absorb nutrients from food.

• Changes in metabolism: cancer can sometimes change the way your body uses energy, protein and other nutrients. This can contribute to loss of weight and muscle and may be part of a condition called cancer cachexia.

Managing Symptoms

Understanding what may be contributing to your weight loss is an important first step. If symptoms or other issues are affecting how you eat, we want to manage these as well as we can.

What helps will depend on what is going on. It might mean reviewing medication or when you take it, getting better control of pain or constipation, making changes to what or how you eat, moving your body where you can, or getting support with anxiety, stress or sleep. Often, it's a combination of things.

You can find more help with managing side effects such as nausea, constipation, diarrhoea and taste changes in my blog Nutrition Tips to Help Manage Cancer Treatment Side Effects.

Nutritional Strategies to Help Manage Cancer-Related Weight Loss

When you're losing weight, we're not only thinking about the number on the scales. Maintaining muscle mass and strength is really important too.

The aim is to help you get enough nourishment, particularly protein, while making eating as manageable as possible. Moving your body where you can is another important part of helping to protect your muscle and strength.

We can also look at ways to get more nourishment into the food and drinks you're already managing.

1. Eat little and often

If large meals feel overwhelming, or you fill up quickly, smaller amounts more often can be much easier to manage. Try:

• Aiming for 5-6 smaller meals or snacks throughout the day.

• Eating by the clock if your appetite isn't giving you reliable signals. Setting a reminder can help.

• Using a smaller plate or bowl if a large portion feels overwhelming.

• Keeping easy, nourishing snacks within reach, such as yoghurt with fruit and nut butter, overnight oats, cheese and crackers, chia seed pudding, or hummus and oatcakes.

If you fill up quickly, try sipping drinks between meals rather than having a large drink just before eating.

2. Include protein throughout the day

Protein is particularly important when you're losing weight because it helps to maintain muscle mass and supports repair and recovery.

Try including a protein-rich food at meals and snacks throughout the day. For example:

• Add extra meat, poultry, fish, tofu, beans or lentils to soups, curries and casseroles.

• Choose snacks such as boiled eggs, hummus with oatcakes, Greek yoghurt with berries and nut butter, cheese and crackers, or edamame beans.

• Use milk rather than water to make porridge, add Greek yoghurt to smoothies, or stir cottage cheese or grated cheese into scrambled eggs.

• Add protein powder to porridge, yoghurt or smoothies. You can find more ideas in my guide to creative ways to use protein powder.

3. Fortify your meals and snacks

Fortifying food means adding extra nourishment without making the portion much bigger. This can be particularly useful if your appetite is small or you feel full quickly.

Depending on what you enjoy, you could:

• Drizzle extra virgin olive oil over vegetables, soups or pasta.

• Add nut butter to porridge, yoghurt, smoothies or toast.

• Add grated cheese to scrambled eggs, mashed potato, soup or pasta.

• Use full-fat Greek yoghurt, cream or crème fraîche where they work well.

• Add milk powder to milk, porridge, sauces or milky drinks.

• Sprinkle ground nuts or seeds over cereals, yoghurt, soups or salads.

• Add avocado to sandwiches, toast or smoothies.

A few additions to foods you're already eating can make quite a difference.

4. Choose nourishing fluids

Drinks can be another good opportunity to get some extra nourishment in.

Try:

• Smoothies made with fruit, yoghurt, milk or a fortified plant-based alternative.

• Milky drinks, such as a milky coffee, turmeric latte, hot chocolate or malted drink.

• Milkshakes with fruit, yoghurt, and nut butter.

• Small mugs of nourishing soup.

• Vegetable juice.

If you're struggling to meet your needs with food and drinks alone, oral nutritional supplement drinks and products can be useful. Some can be bought over the counter and others may be prescribed by your GP or treatment team.

5. Omega-3 fatty acids and muscle mass

Omega-3 is also something I think about when I'm supporting someone who is losing weight or muscle.

Oily fish such as salmon, sardines, mackerel and trout are particularly good sources of the long-chain omega-3 fats EPA and DHA. If you eat fish, aim to include oily fish regularly if you can.

Walnuts, chia seeds and ground flaxseed provide a plant-based form of omega-3 and are useful nourishing additions to meals and snacks.

There has been interest in whether omega-3 supplements may help with loss of weight and muscle in cancer. The evidence is not strong enough to recommend them routinely, but there may be situations where I would consider them individually.

If you're thinking about taking an omega-3 supplement during cancer treatment, check with your cancer team or pharmacist first to make sure it is safe to take alongside your treatment and other medications.

But All I Fancy Is the Foods I 'Shouldn’t' Be Eating

This is something I hear a lot from clients: “All I fancy is ice cream, crisps or chocolate.” Often, the worry is that these aren't the foods they feel they should be eating.

When your appetite is poor, this isn't the time to put more pressure on yourself to eat perfectly. If something appeals to you and you can manage it, that's important.

My clients know I much prefer thinking about what we can ADD, rather than what to subtract. Sometimes that means enjoying the food you fancy exactly as it is. Other times, there may be an opportunity to add something alongside it or build on it to bring in a little extra nourishment.

• Ice cream: add fresh or frozen berries and sprinkle over some chopped nuts or seeds.

• Chocolate bar: enjoy it with a handful of nuts and dried fruit, or break it into pieces and make your own trail mix.

• Crisps: have them alongside hummus, cheese, guacamole or a yoghurt-based dip.

• Toast: add peanut or almond butter, eggs, avocado, cheese or hummus.

If your weight continues to fall despite making changes to your food and drinks, do let your cancer team know so they can help support you.

Movement and Muscle

Food is only one part of protecting muscle. Moving your body is important too.

Continuing to use your muscles helps to maintain strength and physical function. This might mean walking, getting up and moving regularly during the day, or including some resistance or strength-based exercise.

What is appropriate will depend on your treatment, symptoms and how you're feeling, so this isn't about pushing through when your body needs rest. Even small amounts of movement can be really worthwhile.

Getting Support

If you're losing weight or finding it difficult to eat enough, I can help. Together, we can develop a personalised nutrition plan to help protect your weight, muscle mass and strength.

Find out about my personalised nutrition support programmes.

Updated October 2026

This blog is for general information only and is not a substitute for personalised medical or dietetic advice.

References

Muscaritoli M, Arends J, Bachmann P, et al. (2021). ESPEN practical guideline: Clinical Nutrition in cancer. Clinical Nutrition, 40(5), 2898-2913.https://www.espen.org/files/ESPEN-Guidelines/ESPEN-practical-guideline-clinical-nutrition-in-cancer.pdf

Roeland EJ, Bohlke K, Baracos VE, et al. (2020). Management of Cancer Cachexia: ASCO Guideline. Journal of Clinical Oncology, 38(21), 2438-2453.https://ascopubs.org/doi/10.1200/JCO.20.00611

Ligibel JA, Bohlke K, May AM, et al. (2022). Exercise, Diet, and Weight Management During Cancer Treatment: ASCO Guideline. Journal of Clinical Oncology, 40(22), 2491-2507.https://ascopubs.org/doi/10.1200/JCO.22.00687