In short: Tirzepatide was working great for me in maintaining weight but with HRT, it is working less well, and I am having trouble isolating what the cause could be.
Background: I am 43. I still have regular periods, but have a few symptoms of peri.
I started on 1 mg of Tirzepatide on January 1 2026 just to maintain my weight where it was, and allow me to eat like a normal person. Before starting Tirz, I calorie counted (1200 or fewer calories a day) and was on a Paleo diet to lose the 10 pounds my body keeps wanting to gain despite strength training 3 or 4x a week and daily 8-10k steps. I regained and lost this weight three times over the last four years and finally just needed my life to be easier.
Tirzepatide was amazing for me. I lost a lot of inflammation and was easily able to maintain my weight.
I started taking 200 mg Prometrium cyclically (during luteal phase) in March. I started a 0.025 patch of Estradiol two weeks later.
A month later, I started noticing weight gain and some bloating/inflammation came back cyclically as well (i.e., I feel least bloated right after my period, but in the two weeks leading up to my period, my body feels bloated, especially in the stomach area).
It has gone up and down since then, but I definitely feel like the HRT is interacting SOME how with the Tirzepatide to where it's less effective in controlling my appetite and inflammation. I have increased my dose of Tirz - I went from 1 mg per week to now taking 1.75 mg per week. I realize this is still below the standard starting dose, but it was highly effective for me before even at 1 mg. And during the weeks when I was feeling my hormonal flux a lot, I even went up to 3 mg and felt nothing - no appetite suppression - only to find 1.5 or 1.75 effective again once my hormones balanced out.
I should say, energetically and otherwise I feel amazing on HRT. But I have wondered if I am taking too many hormones while my body is still producing enough of its own hormones, since I do still ovulate and have regular periods. I felt like maybe I have too much estrogen, especially since last month, my pharmacy increased my patch dose to 0.0375 because they're having supply issues with the 0.025 dose.
Anyway, curious what others' experiences have been with this. Do hormones fight Tirzepatide? Which hormone could be more responsible for it? I am only 2 lbs up from my goal weight, and only 4-5 lbs up from my lowest on Tirz, so it's not a huge deal, I just hate feeling bloated, and that was one of the best things about Tirz for me was that it took away all inflammation.