Weight gain

Weight gainYou may have gained weight during treatment. There are certain treatments that cause weight gain. For example, chemotherapy and hormonal therapy for breast cancer or prostate cancer. Weight gain may happen after treatment and can be distressing.

On this page:

> What causes weight gain?
> Practical tips
> Nutritional tips

What causes weight gain during cancer treatment?

It’s not entirely clear what causes people to gain weight during treatment. It seems that a combination of different factors is involved.

  • As a woman, you may have experienced an early menopause due to the treatment.
  • You may have started eating more or differently or may have become less physically active.
  • There may also be a fluid build-up under the skin (oedema) or in the abdomen.
  • If you were already overweight before treatment, this may have increased during treatment.
  • Some cancer treatments, such as hormone therapy for breast or prostate cancer, may cause weight gain.
  • Some medicines, such as steroids, may increase your appetite, meaning you want to eat more than usual.

Practical tips

  • Try to not eat too many snacks. This applies to both sweet and savoury snacks.
  • Full-fat dairy products contain more fat than the low-fat and semi-skimmed varieties, so choose products such as skimmed, fat-free cottage cheese, and low-fat or fat-free yoghurts.
  • Avoid adding extra sugar to drinks or cereal.
  • Drink water, sugar-free squashes, coffee and tea without sugar. If you choose soft drinks such as cola, go for the sugar-free options instead.
  • Ask for help. A dietitian can advise on changes you could make – ask your doctor for a referral.
  • Sit at the table when you eat, take your time, and don’t eat too quickly. This way you recognise the feeling of fullness better and you are less likely to eat too much.
  • If possible, try to increase how physically active you are. Get more tips and advice >

Nutritional tips

  • If you feel the urge to snack, choose low-calorie versions. Examples include fruit, low-fat dairy products without added sugar, wholemeal bread or toast with low-fat cheese or chopped raw vegetable sticks with reduced-fat hummus.
  • Try to eat regularly and spread your meals evenly throughout the day. Try to limit your portions.
  • Fibre-rich food fills you up more. Examples include wholemeal bread, brown rice, wholewheat pasta, pulses, and generous portions of fruit and vegetables. (If you have had a part of your bowel removed, consult your healthcare team before adding fibre-rich foods to your daily diet)
  • Protein foods can help you feel fuller for longer. Good sources include lean poultry (eg skinless chicken and turkey), fish, low-fat dairy, eggs and pulses such as beans.

Even if you’re trying your hardest by paying attention to your diet and being more active, you may still gain weight due to cancer treatments. This can be very frustrating. Remember – if you hadn’t paid attention to your diet and how active you are, your weight gain could be greater.

Where next?

> Get tips and advice on increasing your activity levels

> Read all our Cancer Prevention Recommendations

> Why not visit our recipes for lots of healthy meal suggestions that are lower in fat and sugar

In association with

NIHR cancer and nutrition collaboration logo


British Dietetic Association logo