Daily Life

Nutrition

If you have been diagnosed with metastatic breast cancer (mBC), eating well can support your overall health. A balanced, personalized diet can help you stay strong, maintain your weight, support your immune system, and manage treatment side effects.

How Treatment Can Affect Eating

Cancer treatments can change how your body digests food. While some people are able to eat normally, others may notice changes in appetite, digestion, or taste. These effects can shift over time and vary from person to person.

Common side effects of systemic therapy (like chemotherapy or targeted therapy) include:

• Reduced appetite
• Nausea or vomiting
• Changes in taste or smell
• Mouth sores, constipation, or diarrhea
• Increased appetite and weight gain (in some cases)

It is normal for your nutritional needs and eating habits to change during treatment. You may go through periods when eating is more difficult and will need to adjust your eating plan to help you feel your best.

What to Eat

Eating smaller meals more often throughout the day can help manage symptoms like nausea or fatigue. Focus on foods that are nourishing, easy to digest, and provide steady energy, such as:

• Fruits and vegetables for vitamins, antioxidants, and fibre
• Whole grains like oats, brown rice, or quinoa for long-lasting energy
• Lean proteins such as chicken, fish, eggs, tofu, or legumes to maintain strength
• Healthy fats like avocado, olive oil, and nuts to support a balanced weight
• Smoothies, soups, or shakes if solid foods are harder to manage

Some people may need more calories and protein than usual to prevent weight or muscle loss. A dietitian can help you build a plan that fits your needs and complements your treatment.

What to Limit

Some foods may increase inflammation, affect digestion or energy levels and be harder to tolerate during treatment. Certain foods, such as grapefruit, and other drugs may even influence how your body responds to treatment. You may want to limit:

• Alcohol
• Fried or fast foods
• Processed meats like bacon or sausage
• Foods high in added sugars or refined carbs

Listening to Your Body

There is no one-size-fits-all diet for mBC. Your needs may also change from day to day, depending on how you feel. Some days, you might only want soft or bland foods. Other times, eating anything at all might feel difficult, and that is okay.

The goal is not a perfect diet. It is about finding what is manageable and nourishing for you. Focus on supporting your strength, comfort, and quality of life.

Supplements and Special Diets

Be cautious with supplements, herbal remedies, or “anti-cancer” diets you see online. Some products can interfere with your treatments or cause harmful side effects. Always speak with your healthcare team before starting anything new.

Getting Support

If you are struggling with eating or want help creating a personalized nutrition plan, reach out to your healthcare team. A registered dietitian with experience in cancer care can help you adjust your diet to support your energy, digestion, and treatment goals.

Eating well can help you feel more in control of your health and improve your quality of life during treatment.

The Canadian Cancer Society has a database that can be used to find local support services in your area. You can access it below:

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