Tips for reducing chemotherapy weight gain during breast cancer treatment

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Contrary to the word on the street, most patients getting chemotherapy have a tendency to gain rather than lose weight. This seems to be particularly true for breast cancer patients.

Research has found that weight gain increases the risk of breast cancer recurrence. After breast cancer surgery, many women experience negative changes to their body image, and weight gain can exacerbate this.

As a medical oncologist, I hear from my patients often that they didn’t expect to gain weight during treatment for breast cancer. We aren’t sure exactly why women tend to gain weight during treatment for breast cancer, but it’s likely a combination of things: reduced physical activity due to fatigue; altered taste, sore mouth and changes in digestions makes healthy foods less appealing or uncomfortable to eat; and the chemotherapy itself causes changes to the body’s metabolism.

To reduce the risk of recurrence of breast cancer and to help maintain a positive body image, I talk to my patients about maintaining their weight throughout treatment. For some women, we talk about slowly starting to lose weight (of course no fad dieting!), which happens quite naturally if they eat healthier and begin or increase exercising.

Top 10 Tips to Avoid Weight Gain and Maintain Your Weight and Well-Being While on Chemotherapy

  1. Eat breakfast. It keeps your body from going into starvation mode where it wants to hang on to every single calorie.
  2. Keep healthy snacks close. When that abnormally intense hunger hits, you’ll want to eat anything you can get your hands on quickly. So have cut up or snack-size vegetables (and some low-fat dips) within easy reach.
  3. Keep unhealthy food out of reach. This can be challenging if the people you live with want their junk food, but you can tell them that depriving themselves for a while is a great way for them to support you. On the other hand, it’s fine to have the odd treat, even daily.
  4. Eat fruit in moderation. Fruit is a great source of essential vitamins but also contains lots of sugar (especially grapes, bananas, and mangoes). So aim to have at least two servings of vegetables for every serving of fruit. Juicing is not essential. Grinding up fruits and vegetables isn’t any healthier than eating them whole. If you do juice, make sure that you drink all the pulp too, as the fibre fills you up and fights constipation.
  5. Carbs aren’t all bad. Baked potatoes (with their skins), brown rice, buckwheat (kasha), whole wheat pasta, and quinoa have lots of vitamins and healthy fibre. Just keep the portions moderate.
  6. Protein is important. Try to have at least a half-cup of lean protein at every meal. Unsweetened yogurt, cottage cheese, lean meat, chicken/turkey without the skin or coating, chickpeas, beans, or low fat soy products (soy does not make breast cancer grow!) are all excellent choices. Nuts are also an excellent source of protein but high in fat so limit nuts to one handful (or 1/3 cup) per day. Beans, buckwheat and quinoa are grains but have lots of protein.
  7. Eat supper early. If you’re not ravenously hungry, you’ll be less likely to overeat.
  8. Limit snacking after supper. People tend to be least active after supper so anything you eat at that time gets stored as fat. It will also make you less likely to be hungry the next morning (see tip #1). Water and unsweetened tea is always fine. If this is a time when hunger hits, please see tip #2.
  9. Exercise. At least 30 minutes every day. It not only burns calories while you’re doing it but also revs up your metabolism so you’re burning more calories all day. Exercise can also help cope with side effects. Find activities you enjoy so exercise becomes fun and relaxing rather than a chore. Don’t forget simple things like taking the stairs instead of the elevator, dancing, and brisk walking (outside or in a mall if the weather is bad). Wellspring has exercise programs available specifically for those undergoing cancer treatment. You can also find an infinite number of varied home workouts online (eg. or If you haven’t been active, talk to your care team.
  10. Mental health is health. Many women have a difficult time coping with their diagnosis and/or treatment. Reach out and get support. We have sensitive, caring and experienced social workers, psychologists and psychiatrists available. Ask your doctor or nurse for a referral.

If you have more questions or concerns about eating while on chemotherapy, please speak to your healthcare team.

About the author

Dr. Ellen Warner

Dr. Ellen Warner is a medical oncologist at Sunnybrook’s Odette Cancer Centre.