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how to lose weight on tamoxifen

Mlesley Member Posts: 1
edited September 2021 in Working on Your Fitness

After 8 months, my doctor took me off tamoxifen 2 weeks ago. I've gained 15 pounds on this poison. I exercise for at least an hour each day (4-5 mile walk/runs and weight machines). I eat healthy and always have. I've never had a weight problem. I actually was anorexic in high school and college but was able to learn how to balance eating and exercise for a healthy lifestyle. Now at 41 I am gaining weight- mainly around my midsection. I look pregnant. I fall to pieces when i get on the scale and see that the number is still creeping up. I fall to pieces when i see myself in the mirror. I fall to pieces when I try to put on a pair or shorts or pants and i can't button them. I am doing everything I can - exercise, diet - and the weight keeps creeping up. Tamoxifen also gave me horrible mood swings, depression, increased anxiety and pretty much dried everything up (hair, nails, eyes, etc). Because of this my doctor is giving me a 2 month "break" from the meds to see if there are any changes.

So far my weight gain seems to be slowing down, but its still creeping up. All other side effects are SIGNIFICANTLY better since I stopped the tamoxifen. I'm begging for help. How can I lose this weight? Why am I gaining so much in my stomach? It is just not fair. I'm still trying to come to terms with my body post mastectomy and reconstruction- and now the medicine that is supposed to keep the cancer from coming back is just making me crazy and fat - it just makes me cry. I'm exhausted. I am trying so hard and I keep gaining. Help!!!!


  • nancy2581
    nancy2581 Member Posts: 407
    edited August 2017

    Hi Miesley - I'm sorry you're going through this. I'm on tamoxifen and have gained 10 lbs and yes it worries me that the scale keeps going up, but it has seemed to stabilize for the last 8 months. They say tamoxifen doesn't cause weight gain. I got thrown into menopause so I'm sure that isn't helping.

    Have you had your thyroid tested? If your thyroid is out of whack it could cause the weight gain and you can't lose any weight because of it Just a thought. I also take just 5 mg lexapro to balance the mood swings. I dropped from 10mg because I was convinced it was causing the weight gain. After dropping to 5 mg I stabilized. Could be a coincidence.

    Hope you get to the bottom of this. I know exactly what you're going through.


  • momoffab5
    momoffab5 Member Posts: 1
    edited October 2017


    I am so sorry you are going through this. I would suggest, too, that you ask to have your thyroid tested if not done so already.


    I had put on some weight and was blaming on stress. The same dr visit that prompted my breast cancer diagnosis also revealed my crazy low thyroid. I started taking medicine for it and just about the time I felt some relief with fatigue (no weight loss) I had surgery and radiation throwing it out of whack again. In comes Tamoxifen putting me into full blown menopause. Here I sit with constant fatigue and fat!!!! Have you found any help to losing the extra pounds?

  • 123JustMe
    123JustMe Member Posts: 169
    edited March 2018


    I’ve been on Tamoxifen since 10/15. Unfortunately for me what worked in losing 65 pounds was switching to a plant based diet and joining a gym and working out. I’ve been able to maintain the weight loss with this combination..... Good luck

  • ksusan
    ksusan Member Posts: 461
    edited October 2017

    I've only been able to lose weight with a plant-based diet.

  • Dm39
    Dm39 Member Posts: 5
    edited March 2018

    Hi Mlesley. I too am post double mastectomy and just started taking tamoxifen. I have a thyroid disorder and was just starting to regulate it and lose some weight when all of this came about. I read somewhere that not only do women who have had breast cancer have a 50% higher risk for thyroid cancer, but that low iodine can actually cause your body to produce extra estrogen. Lucky us right. Well i have been on this tamoxifen for two weeks and already I am gaining weight, have mood swings, and can barely walk on my legs from the joint pain. I really don't know how women do it for 5 yrs! I feel your pain. Getting used to your body post mastectomy is hard enough! Fyi, I found out about my thyroid by doing whats called a barns test. Take your temperature every morning for two weeks before you get out of bed in the morning. Before you pee. Take the results to your endocrinologist and if your temperature is off they can have your iodine levels checked. I found out when my temperature was down to 91.3° consistently and my body was going into shock from hypothermia. All my previous generic thyroid testing came back normal. I could have died. Then low and behold I found a lump about 8 months later. Could've been my thyroid that caused my cancer. I definately feel they are related. Also if you can, research medical medium. He is the author of a few books on foods to heal just about any illness. Hope this helps good luck on your journey. We all walk this alone but we are not alone. Look at all the beautiful women out here going through this together. This site and all of your stories has helped me so much. God bless!