top of page
  • Writer's pictureErin Benner

Worried About Weight Gain After Breast Cancer Treatment?

Updated: May 9, 2023

As an outpatient cancer dietitian I would often get referrals from Oncologists to see women for weight loss during breast cancer treatment. “Not appropriate!” I’d think, putting it to the bottom of the consult pile. My primary role was helping with side effects and reducing weight loss in people being treated for cancer. Treatment is a stressful time, with a plethora of side effects that can benefit from nutrition support. Weight loss can be difficult at the best of times, so addressing it during treatment did not seem like something I could treat in a one hour session. But MOST women going through breast cancer treatment gain at least 5lbs and usually don’t return to their pre-treatment weight. Now, I work with many women who are dissatisfied with their weight after treatment. They are often getting pressure from their doctor to lose weight to reduce the risk of recurrence, feeling uncomfortable in their body and dealing with food fears and cravings. Unfortunately, this can bring up a lot of guilt and confusion during a time when they’re trying to figure out how to recover and shift back into “normal”. They may start scrolling through diet posts again, trying to figure out what’s the best new weight loss method, only to lose, fail and rebound sinking deeper into post treatment depression, fatigue and brain fog. Why you’ve gained weight after treatment is also the key to how to balance your weight and shift into a body you feel better in.

In this series I’ll be showing you the reasons for weight gain after a breast cancer diagnosis, tools and strategies to limit treatment weight gain and supportive ways to balance your weight after treatment.

Weight Changes Through Diagnosis.

The heartbreaking diagnosis of Breast Cancer can immediately change the relationship you have with your body. For some, they go numb, not listening or feeling into the body’s cues and messages. For others they dig into confusion, guilt or denial. The relationship you have with your body will also affect your relationship with food and appetite. Some women start to shift their body weight through the difficult weeks of appointments and treatment plans. Skipping meals, over eating comfort foods, receiving food and gifts from loved ones or becoming increasingly concerned about what foods are safe to eat can be major influencers of weight change.

What Surgery Takes and Leaves Behind.

Many women describe an increased appetite when they get home after surgery. Why? Because their body is asking for extra nutrition for healing! But many women aren’t eating enough of the best foods or enough of the most important nutrient. Pair that with decreased movement for a few weeks and they quickly lose muscle. Now that body composition has shifted, weight gain becomes increasingly likely.

Cathy felt “puffy” after surgery, IV fluids and constipation made her feel bloated. She was relieved to be home but too exhausted to get back to the kitchen. She and her family ate meals provided by friends and family as well as convenience foods and relied more heavily on eating out. Cathy didn’t have much of an appetite but everyone around her encouraged her to eat, appealing to her sweet tooth and love of home baked treats. When she was seen at the cancer center a few months later she was shocked to see how much weight she had gained. Then the guilt and confusion set in.

Hormone Therapy Does Not Cause Weight Gain.

Maybe Tamoxifen isn’t supposed to cause weight gain, but it’s still one of the main concerns when women start taking it. Of course many women see changes in their body through menopause, so it’s unrealistic to think hormone therapy is not affecting weight and body composition. The horrors of hot flashes, sleepless nights and rampant cravings leave women feeling like they deserve a medal, or at least a treat, for going through all this!

When Sandra talked to her doctor about her weight and concerns about Tamoxifen she was disputed by her doctor saying “Tamoxifen doesn’t cause weight gain.” Confused, she was told to just eat less and move more. Sandra felt dismissed, her concerns weren’t heard or validated and now she felt like she brought this on herself. She struggled all year, denying the changes her body was going through.

Radiation Increases the Burn.

If you weren’t eating the right foods for healing after surgery, radiation can continue to burn through muscle mass. Not to mention the daily appointments, throwing off healthy routines and eating habits. Fatigue and brain fog can really set in during this time, often lasting months beyond when radiation finishes.

“Ringing the Bell” was not the end of the cancer battle for Megan. She struggled as she tried to return to work. She doubted her abilities and skills as she questioned who she really was after the treatment. She sure didn’t feel like herself! Spending longer days at the office trying to keep up, she came home exhausted and completely tapped out each day. Dinner was the easiest foods she could get in but it didn’t refuel her for the next day. Until we built a meal framework that provided her body with the energy and nutrition it deeply needed. Her energy levels improved dramatically, giving her the strength she needed to make intentional choices to rebuild her body and lifestyle after treatment.

Aren’t I Supposed to Lose Weight During Chemo?

Most people think of nausea and poor appetite when they imagine chemotherapy. Fortunately, modern anti-nausea medication schedules have drastically improved treatment-related nausea. But appetite can still be far from normal. Dexamethasone is a common anti-nausea that can increase appetite and fat, fuelling food cravings and high blood sugars.

Chemo side effects can make eating tough. Alternating diarrhea and constipation. Taste and smell changes. Mouth tenderness. Fatigue. Pain. They can all affect your interest in food and leave you questioning, “What can I actually eat?!” This is also the time where I see massive changes in body composition. Severe weight loss can delay treatment and add months to the recovery period. Some get lost as they go deeper and deeper into the chemo fog, making it hard to orientate to a healthier way of being.

Judy felt terrible during chemotherapy. Her appetite was off, she couldn’t sleep and she missed the comforts of her regular routines. Although she was concerned about gaining weight, she was just eating what she could and doing the best she could during treatment. It felt like everyone around her had a food tip. Don’t eat sugar. Don’t eat meat. Have you tried gluten-free? Asparagus can cure cancer! A month after her final chemo cycle she felt she should be switching into “normal” mode but she didn’t feel normal. Her appearance totally changed when she lost her hair, her body was unrecognizable when she looked down and she had gained 35lbs. She wondered if she should be cutting back on calories, even though her meal portions were already much smaller than before treatment. Cravings for high calorie, processed foods were stronger and more frequent than she had ever experienced before. She wanted to be working out again but spent most afternoons on the couch fighting sleep. As we worked together she realized that she didn’t need less food, she needed more nutritionally dense foods to boost her body during its recovery phase. Weeks later she was seeing a full scalp of baby hairs sprouting and noticing she had more energy in the day. She started building back supportive routines while being kind and compassionate to herself. Once again she was able to find a sense of control in her lifestyle choices as we worked with her current state to get her into the recovery zone.

As you take on these layers and layers of difficulties through treatment it adds to the weight of your life, and your body. You didn’t just “gain 20lbs after treatment”. What your body needs is not severe restriction but compassionate support to recover and heal. I work with women through coaching packages to take them from their confused and distressed state into a space of improved energy, motivation and self-confidence. A space where they can heal and find love for their body and themselves.

If this has been your experience through breast cancer treatment and you are looking for support, send me a direct email at

Savour Nutrition is launching a small group cohort program for women diagnosed with breast cancer wanting to nourish their body and heal their relationship with food. With the best foods for you, the right supplements and powerful strategies you can start feeling better and investing in your best self.

Join the waitlist for more information!

→ Next post will be about strategies you can use during treatment to minimize weight gain.

8 views0 comments


bottom of page