Do aromatase inhibitors (like anastrozole) cause weight gain?

@ riverwatcher
If you look at all the possible side effects of anastrozole on Mayo's website, weight gain is listed. On the other hand, I lost weight on it… about a pound/month for the first two years. It had been my practice for years, however, to walk a mile/day on a treadmill. Then came Covid-19 and the gym closed… and the weight loss ended as I was unable to walk outside due to chemo-induced peripheral neuropathy. One might conclude that the anastrozole did not make me gain weight, and that I lost weight on it when combined with the exercise.

A few pounds now are being added. However, I also note that I have not changed my diet in response to the lack of exercise. It's all a balancing act with trade-offs at every turn.

I believe there is. As others have said, it is a side effect that I have experienced up close and personal. And it seems to be belly fat,predominantly. My activity levels are higher than a year ago but no weight loss is happening. Of course, I look at it as,”if weight gain is the most serious side effect I am experiencing,I can live with it (unhappily).

That's the one side effect that I seem to have. In spite of more exercise (stationary bike, because I need to use a walker) and strict attention to diet. But I feel the same as you – if that's the worst side effect, I can live with it.

I am on Anastrozole and am gaining a lot of weight. Anyone else?

Hi Crazydaisy, @riverwatcher asked this same question a while back so I moved your question to the existing discussion about weight gain and anastrozole. @sparklegram @cancersucks @farmgirl1556 @trixie1313 I believe have also experienced the side effect of weight gain with aromatase inhibitors, include anastrozole.

Daisy, have you made any adjustments to diet or activity to help manage the weight gain?

@crazydaisy Yep – it's a problem, especially if you're under 5 feet! I didn't do well with anastroze or letrozole and have been on exemestane now for about 1 1/2 years. I find that I need to write down what I eat. Protein for me is 2 poached eggs for breakfast and 3.5 oz of lean meat. Veggies are dark green and I stay away from dressings. My fruit of choice would be apples as some fruits contain a lot of sugar. I've lost 20# since January and have another 40 to go, but it moves slowly. I do walk 2-6 miles a day and also do a core/free weight/stretch cord exercise program twice a week for breast cancer patients. Also – I stay way from sodas and mostly drink lots of water. It goes slow and there can be setbacks, you just need to stay focussed. Hoping you start to see results soon.

I actually went on weight watchers and lost what I needed to lose and have maintained it. I have been on all 3 AI’s and now waiting to try Tamoxifen on the 23rd when I meet with the oncologist. So have no idea what that will do for the weight.

bluebird70—I'm curious about the different AI's. Did you have side effects or why the changes? I am supposed to start Anastrozole and am looking at being in a study group.

I started on Anastrozole 1mg several months ago. I am in a research project through Dr Sideras about effective dosages of Anastrozole. I would contact Dr Sideras’s office and ask about it.
I have severe fibromyalgia and this Rx has intensified my insomnia, chronic muscle/joint pain, fatigue and it’s caused an increase in mood changes (anxiety,depression) on top of those I experienced with fibro each day. 😞

Waiting for results of blood testing of estrogen levels. Praying Anastrozole is working.
Thinking of changing to Letrozole which research shows as causing less side effects.

Anyone out there with fibromyalgia and taking an aromatase inhibitor? What side effects are you experiencing?

Sandyrob I started with anastrozole from September last year to Christmas and had vicious headaches, muscle pain the whole gambit, two weeks off went on exemestane and pretty much the same symptoms and was on them from December to February and lastly ion Letrozole and way different symptoms like trigger thumb in both hands and severe stomach issues. I have now been off Letrozole now for a month. My hands are much better the stomach issues have subsided but still have a little bit and I feel great. It is interesting what you do tolerate while on them. I see oncologist next week to determine my next steps. I believe it will be Tamoxifen but I want to know more about it.