Weight gain during or after breast cancer treatment can be unexpected and distressing, but it’s not uncommon. We look at why some people put on weight, and give some tips on how to start losing weight after treatment.

Losing weight after breast cancer treatment

Why have I gained weight?

There are several reasons why someone might put on weight during or after treatments such as chemotherapy.

  • Your diet may change during treatment – for example some people crave and eat more higher-calorie foods, or their tastes may change during chemotherapy.
  • Steroids, often given with chemotherapy, can cause people to put on weight.
  • The menopause, brought on by treatments such as hormone therapy or chemotherapy, can lead to weight gain.
  • You may be less active that usual when having or recovering from treatment. 

How can I lose weight after treatment?

Losing weight is not always easy and can take time. But there’s a good reason to maintain a healthy weight, besides the way you look. ‘There’s evidence that being overweight could increase the risk of breast cancer coming back,’ says Lucy Eldridge, dietetic team leader at the Royal Marsden NHS Foundation Trust.

If you want to lose weight it’s important to set a realistic goal. Aim to lose about 0.5–1kg (1–2 pounds) a week through healthy eating and doing regular physical activity.

Avoid fad diets that promise rapid weight loss. ‘Often they’re not based on scientific evidence,’ says Lucy, ‘and you’re more likely to keep the weight off if you lose it slowly and steadily.’

» Read our four common weight loss myths dispelled

Eight weight loss tips to get you started

The best way to lose weight is to make some simple, sustainable changes to the way you eat and drink, and to fit some physical activity into your everyday life.

Here are some tips to get you started.

1. Reduce your portion sizes

There are several different ways you can cut down your portion sizes, such as using a smaller plate, not going back for seconds, or having a healthy starter before your main meal.

2. Choose wholegrain bread, pasta and cereals

These foods are higher in fibre than their white varieties. Foods that contain lots of fibre can help you feel fuller for longer. 

3. Eat more fruit and veg

Fruit and vegetables are not only packed with essential vitamins and minerals, but they’re also high in fibre and low in calories. Aim for at least five portions a day.

4. Swap soft drinks

Sugary soft drinks are often high in calories but won’t fill you up, so it’s easy to drink a lot of them. Swap sugary drinks for lower calorie alternatives like water on unsweetened tea and coffee with a small amount of milk.

Natural fruit juice also contains a lot of sugar, so try not to drink more than one glass a day.

5. Drink less alcohol

Alcoholic drinks tend to be high in calories but have little nutritional value. For example, a large glass (250ml) of wine contains around 190 calories, similar to four ginger nut biscuits.  So cutting down on the wine will help you cut calories too.

6. Limit junk food

Cut down on unhealthy snacks like biscuits, cakes, chocolate and crisps. Look for healthier alternatives to snack on, such as fresh fruit or unsalted and unsweetened popcorn.

7. Take care when eating out

Check the menu for healthier options when eating out, and remember that takeaways can be high in calories.  

8. Get moving

When it comes to losing weight, it’s important to do some regular physical activity in addition to eating healthily. This should be of moderate intensity, which means it should increase your heart rate and make you break a sweat but you should still be able to hold a conversation.

The important thing is to start slowly and build up gradually. We’ve got plenty of tips on how to get active.

Need more support?

Your GP or practice nurse may be able to give you more information about healthy eating and suitable exercises.

Some people find the support from a local weight loss scheme or club helpful.

The NHS has a free 12-week weight loss guide.

Diet and breast cancer