Progesterone reduces both estrogen and DHT. I'm not sure about testosterone though. RP said this about progesterone:unexamined_whimsy said:Haha yeah. Actually a google search "estrogen hypertrophy bodybuilding" should keep you engaged.
I have personally seen the labs of several of my bodybuilding and powerlifting friends complaining of low libido. Their T levels are often surprisingly low, with moderately high estrogen but with good free-T numbers and low SHBG.
I don't think I understand the mechanism of why estrogen aids hypertrophy but my guess would be that the induced swelling causes microruptures in the muscle tissue that once repaired result in a larger muscle. Regarding DHT, it would be an oversimplification to reduce its effects as purely an antagonism of estrogen. Incidentally, DHT also strongly inhibits prolactin. While it is true that the conventional thinking is that DHT is not anabolic, recent studies in mice have shown that mesterolone (Proviron) or 1-methyl DHT is clearly anabolic. In any case, experience shows that DHT and its derivatives are definitely anabolic.
"I have seen my own hairline move with changes in hormones, and I gave a progesterone solution to a couple of balding men who started growing hair in the front where it had receded . Since progesterone is a testosterone antagonist, it can cause the penis to shrink, and if DHEA is used with it to counteract that effect, there's the potential in hypothyroid people for the DHEA to be converted to estrogen. Progesterone's effect is very individual, and I think it's better to concentrate on correcting the basic metabolic processes that cause hair loss." - Ray Peat
"Rubbed into the scalp, with a little oil (or alcohol, if your skin is oily) it can help the hair without so much effect systemically. A large amount of it antagonizes testosterone, shrinks the penis like a cold shower (but doesn't prevent erections), and it can cause tightness of the ducts in ejaculation." - Ray Peat
If both DHT and estrogen decrease, then there is less HPG axis inhibition and testosterone increases. I'm not sure how progesterone impacts the HPG axis and testosterone production though. I know high doses of progesterone would slow or halt penis growth and voice deepening, functions of DHT, but those aren't important. I don't know if it would shrink my testicles or lower testosterone levels. RP said progesterone's action is highly specific, but I have clear indications of a low ratio of it to estrogen, and it would be useful.