Weight loss or gain during breast cancer treatment

Weight changes are a common side effect of treatments for early and breast cancer. Medications, anxiety, and changes in your routine can cause you to lose or gain weight.

This can affect you physically and emotionally. If you need help to keep to a good weight, ask your doctor or a dietitian for advice.

Weight loss

Maintaining weight by eating a healthy and nutritious diet is important during treatment. It helps make sure your body has what it needs to recover.

Some people lose weight during treatment for breast cancer. Some treatments can:

• reduce your appetite (read Poor appetite for tips to improve it)
• change the way food tastes or smells
• make you feel unwell
• cause you to have a sore mouth.

As a result, you may not feel like eating and could lose weight.

Your diet does not have to be perfect. Aim to eat foods you enjoy and do the best you can.

• Ask your GP or treating team for advice if you’re struggling to eat enough to maintain your weight.
• Your doctor may prescribe medication, such as steroids, to stimulate your appetite.
• You may need to increase your kilojoules and protein. This is called fortifying your food. Try to include foods such as lentils and beans, butter, cheese and cream or dairy substitutes.
• Your GP or a dietitian can recommend or prescribe food supplements you can add to food or take on their own. These include:
  • powdered drinks
  • milk-based supplements
  • juice-tasting supplements
  • fat-based liquids
  • energy and protein powders.

If you need further help, you can ask to see a dietitian. They will design an eating program specifically to meet your needs.

Weight gain

Some people gain weight during breast cancer treatment, particularly during chemotherapy.

Weight gain can make people feel guilty and affect their body image and self-confidence. If you have gained weight since your diagnosis, be kind to yourself.

Weight increases can occur for several reasons.

Fatigue: Because of fatigue, some people reduce how much they exercise or stop altogether.

Anxiety: Often people respond to anxiety by eating more.

Steroid medication: Some chemotherapy treatments include steroids to treat nausea and the cancer itself. These can increase your appetite and cause fat deposits, especially in the abdomen. This is most common with long-term use and should go away once you stop the steroids. Your face may look puffier than usual, normally due to fluid retention.

Menopause: Some treatments, especially chemotherapy and hormone-blocking therapy, can cause menopause to start earlier than expected. Menopause and perimenopause change your hormone levels, mainly oestrogen. Oestrogen helps regulate your metabolism and body fat distribution. Lower levels of oestrogen slow your metabolism and make it easier to put on weight.

Loss of lean muscle: less activity and menopause or perimenopause can cause you to lose lean muscle mass. This can decrease the body's metabolic rate. If you don’t reduce your food, this can contribute to weight gain and increased body fat percentage.

What to do if you are concerned

People with breast cancer do not need to follow a special diet or eat particular foods. Aim to eat a healthy balanced diet, using Eat for Health, the Australian government’s dietary guidelines.

If you’re worried about changes to your weight, don’t hesitate to ask your doctor or nurse for help.

It might also help to talk to a dietitian for advice on what foods to avoid or changes you can make to your diet to help maintain a good weight.

Food can be a great source of pleasure. Eating foods that satisfy a craving can give you a positive psychological boost, so it’s important to indulge yourself in a careful way.

A regular, tailored exercise routine can help you maintain a healthy weight. Ask your GP or specialise for a referral to an exercise physiologist with cancer management expertise. They can develop and supervise an exercise program for you. You can also find a directory of exercise physiologists at Exercise and Sports Science Australia.

Managing advice from others

Some people may tell you what they think you should be eating or drinking to improve your health. They might be quite forceful with their advice!

Usually, this is because they care about you. But if they are not helping you, or are causing you distress, try telling them. If you feel uncomfortable telling them directly, ask someone else to speak with them for you.