Just wanted to chime in since my name came up. Yes spironolactone is considered a weak antiandrogen and typically most trans women take 200mg + 4-8mg estradiol in order to get their hormone levels into acceptable levels. So yeah, with 100-150mg of spironolactone and no estradiol you will most likely not be anywhere near the level to achieve full feminization. Especially if your testosterone was high before. But there is still the possibility of partial feminization (gyno, softer skin, issues with fertility, etc.) and sexual side effects.
It could, and I would argue it most likely will, effect your performance in the gym. I used to do bodybuilding prior to transition and it would pretty much be literally impossible for me now that I'm on HRT. I could still make gains but not even close to what I was doing. For me, my muscle started MELTING off at around 5-6 months. And by that point I wasn't even on my full dosage or in the proper female ranges.
Just doesn't seem worth the risk for a normal cis male to me. Even if you don't get these side effects, it's an unnecessary risk for very little benefit to be honest. If you're already on dutasteride you're already taking care of the androgen related hair loss so I don't see the point in even messing with your primary sex hormones... especially as a body builder! :/ There's no telling how spironolactone will effect your hormone levels long term at that dosage as it takes months for most trans women to get into proper ranges. You can't know how strongly it's going to effect you until you've been on it a while.
Sorry I know you say you've carefully considered the side effects but I always make it a point to try to dissuade men from using oral spironolactone whenever I see this threads pop up because I personally feel it is incredibly irresponsible as a cis male who wishes to remain that way.
