Have I Really Let Myself Go? Breast Cancer and Weight Gain


It’s not exactly my fault that I’m overweight.

Weight changes, more specifically, weight gain is a popular topic in any breast cancer circle. Look at online communities and discussion boards and you will see women diagnosed with breast cancer, inquiring about the side effects of breast cancer treatment, and whether that will cause weight gain. Even though some women lose weight while undergoing treatment, I want to share about breast cancer and weight gain.

My Experience

I am 5 years post diagnosis and have gone from a strong and healthy 140 lbs at the time of my diagnosis, to a soft and fluffy 179.4 lbs (I refuse to round up to 180). Sure, I am sitting more, working out less, and enjoying pizza and wine on Thursdays with our Thursday Night Thrivers gang, but I would suggest those are not the only factors contributing to my muffin top. In fact, a study found on PubMed and published in PLOS One claims that “patients who were non-obese at diagnosis showed weight gain, while those who were obese at diagnosis lost weight.”

Yes, it is harder to work out when your body is constantly aching from tamoxifen or an aromatase inhibitor, or experiencing a slowing of your metabolism because you are thrown into premature menopause due to chemotherapy treatment or an ovarian suppressant. Whatever it may be, it starts to feel like the cards are stacked against you.

I’ve certainly met many amazing women who have completely changed their lifestyles after a diagnosis and are cutting out sugars, refined and processed foods, and limiting (or cutting out completely) alcohol. I fall somewhere on the other side of this camp. That is to say, I eat relatively healthy, follow a pescatarian diet, enjoy my fair share of wine (I’m Italian, after all), and during the holidays, I certainly indulge in desserts. Does this make me a bad person? I don’t think so. Does this lifestyle equate to 40 lbs of weight gain? I don’t think that’s the case either.

So What Gives?

I’ve seen a few doctors lately- between my primary, oncology, and specialists for one thing or another- and they all seem to share similar sentiments:

  • “Well, you are getting older,” they say (which no one ever wants to hear).
  • “Being overweight can have other health implications, such as cardiovascular disease or diabetes.” (True statement, but it sounds a little threatening in my already highly vulnerable and emotional state.)
  • “How often do you exercise?” (Gosh, it’s like going to the dentist when they ask you how often you floss! Avoiding eye contact, I mumble something, promising to do better and try harder.)

After these awkward conversations where nothing seems to be going to my advantage, we start to discuss other medications that can help or prevent a whole slew of things such as:

  • High blood pressure
  • Lower cholesterol
  • Support bone health
  • Etc.

So, I went home from yet another doctor’s appointment feeling like this cannot be my reality. Am I actually that unhealthy? Have I let myself go this badly? Sure, I can take some responsibility, but I wanted to do some research and spread the blame.

The Research

According to Foglietta et al., patients treated with aromatase inhibitors are more likely to develop hyperlipidemia, hypercholesterolemia (i.e, high cholesterol, which means your blood has too many fats in it), and hypertension (i.e., high blood pressure), all of which are recognized risk factors for heart disease.

The enzyme lipoprotein lipase (LPL) is controlled by insulin. There is a relationship between estrogen and LPL and be advised that the estrogen hormone suppresses LPL.

  • If LPL is on a muscle cell, it pulls fat into the cell where it’s used for fuel.
  • If LPL is on a fat cell, it pulls fat into the cell and makes it fatter.
  • With less estrogen in the body, LPL can pull fat into fat cells and store it there.” (Breastcancer.org)

Additionally, research published in the Journal of Clinical Oncology found that women treated with an aromatase inhibitor had about a 4.3 times higher risk of diabetes than women not treated with an aromatase inhibitor, which supports the research from Gibb et. al., in the Journal of Clinical Endocrinology & Metabolism who noted that women who received an AI for breast cancer had a greater percentage of body fat and insulin resistance, compared to those with no history of breast cancer.

Ok, so I am not losing my mind! I am on an aromatase inhibitor which is causing me to increase body fat and may lead to insulin resistance, making me a candidate for diabetes, and of course without estrogen, my fat cells are only getting fatter!

Sure there are steps I can take to counter the deleterious effects. In my opinion, my weight gain and potential other comorbidities, may not be entirely my fault! It’s not because I am simply getting older, or that I don’t workout enough.


What we need to include in these conversations with our doctors are the following acknowledgements:

  • Acknowledge that what I am going through is tough.
  • Acknowledge that depleting estrogen will make it harder to lose weight.
  • Acknowledge that many women who have been diagnosed with breast cancer gain weight and that I am not alone in this.
  • Acknowledge that a cancer diagnosis isn’t my fault, and therefore, these side effects are not my fault either.

After acknowledging that you understand how difficult this is, 1 year, 5 years, or 10+ years out from a cancer diagnosis, recognize that I am not choosing to be overweight. Offer to be my partner and support me in reducing the risk of developing long-term side effects from the current treatments I am on.

We Are Not Alone

In case you are one of the many women out there like me who is struggling with life after a breast cancer diagnosis, e.g., fatigue, weight gain, and subsequent other health issues that seem to just be piling on, I see you!

I acknowledge that this is difficult, I know this isn’t your fault, and I know you are not alone because I am not alone either.


Foglietta J, Inno A, de Iuliis F, et al. Cardiotoxicity of Aromatase Inhibitors in Breast Cancer Patients. Clin Breast Cancer. 2017;17(1):11-17. doi:10.1016/j.clbc.2016.07.003

Gibb FW, Dixon JM, Clarke C, et al. Higher Insulin Resistance and Adiposity in Postmenopausal Women With Breast Cancer Treated With Aromatase Inhibitors. J Clin Endocrinol Metab. 2019;104(9):3670-3678. doi:10.1210/jc.2018-02339

Hamood R, Hamood H, Merhasin I, et al. Diabetes After Hormone Therapy in Breast Cancer Survivors: A Case-Cohort Study. J Clin Oncol. 2018;36(20):2061-2069.

Koo HY, Seo YG, Cho MH, Kim MJ, Choi HC. Weight Change and Associated Factors in Long-Term Breast Cancer Survivors. PLoS One. 2016;11(7):e0159098. Published 2016 Jul 8. doi:10.1371/journal.pone.0159098

Why do some people with breast cancer gain weight? Breast Cancer.org, Accessed January 30, 2022. https://www.breastcancer.org/tips/nutrition/after_treat/lose_weight#:~:text=It's%20important%20to%20know%20that,cells%20and%20store%20it%20there.


Posted in: In Treatment, Nutrition/Diet