How treatment can affect eating

Cancer treatment can change how and what you eat in many ways. Some people lose their appetite or find that food tastes different: metallic, bland or unusually sweet. Others have a dry mouth, nausea, or changes in bowel habit, particularly after bowel surgery or radiotherapy to the pelvis. Some treatments, including certain hormone therapies, make weight gain more likely.

These changes can continue after treatment ends, and it is common to feel unsure about what you should be eating now.

Why protein matters

After treatment, your body is repairing tissues and, ideally, rebuilding the muscle lost during treatment. Protein provides the building blocks for that. Combined with strength exercise, eating enough protein helps you regain muscle more effectively than either on its own.

Good sources include fish, eggs, poultry, lean meat, dairy foods or fortified alternatives, beans, lentils, tofu and nuts. Spreading protein across the day, rather than having most of it at one meal, helps your body make good use of it.

If you need to regain weight

If you have lost weight without trying, the priority is getting enough energy and protein, even if that means eating differently from usual healthy-eating advice for a while. Small, frequent meals and snacks are often easier than three large meals, and nourishing drinks such as milky drinks or smoothies can help when your appetite is poor. If you are still losing weight, ask your GP or medical team about seeing a dietitian.

If you’ve gained weight

Weight gain is common after some treatments, especially hormone therapies, and after a period of reduced activity. Gradual changes, such as more vegetables and fibre, fewer sugary drinks and snacks, sensible portions and regular activity, are more sustainable than strict diets, which can also lead to muscle loss. Protein remains important, because the aim is to preserve muscle mass.

Everyday tips

• Eat regularly. Long gaps between meals can drain your energy.
• Drink plenty of fluids, around six to eight glasses a day unless you have been advised otherwise.
• Keep easy, nourishing options in the cupboard for low-energy days.
• If your taste has changed, experiment with herbs, spices, marinades or cold foods.
• Keep alcohol within low-risk guidelines: no more than 14 units a week, spread over several days.
• Be cautious with supplements. High-dose supplements are not recommended unless prescribed, and some can interact with treatment. Talk to your medical team first.

Food is also only part of the picture. Eating well gives you the fuel to recover; activity tells your body what to do with it. Read more in Rebuilding strength and fitness after cancer treatment.

This information is general and does not replace advice from your own medical team. If you have new or worsening symptoms, contact your GP or cancer team. In an emergency, call 999.