IME (yes) using an AI will reduce the size of your gyno (mammory tissue).
I honestly have written this in the sticky a couple of times at least - and in numerous threads but here goes:
Simply that once you have a small case of gyno (not just estrogenic fat deposits), then estrogen that is in your body will all work at that receptor (among many others) to increase or maintain it's size. If there is not much estrogen then there will be no growth of course - and if you are using 1g of aromatisable AAS, then there surely will.
What i have found is this - when using AAS (aromatisable) my gyno lumb swells some, but ONLY temporarily, as when i discontinue the drugs, it drops down to its regular size. This is due to the fact that while there is not enough estrogen acting at the receptor to increase the gland, there is enough to aggravate or inflame it somehow.
Thios is further backed by the SAME thing happening with Tamoxifen - which has an antagonist action at the receptor (in the breast among others). So when on Tamox it swells ever so slightly, but reduces back when stopping use.
Now, if i use an AI post cycle (or when Test levels are not significantly above natural) i find that the gyno is further reduced.. not so much that the tissue is removed or 'cured' but that it is made as small as it can be for the actual mass it is.
I believe this is due to there being almost zero activity at that receptor due to the source of the Estrogen being 'cut off'.
Now none of this is very scientific (i am not degree educated like many here), but i am sure this is what is going on - and in my limited knowledge in that specific area - it fits.
Any activity at the receptor serves to aggravate or maintain the growth. Very little activity seems to allow it to shrink - temporarily - as when estrogen is allowed to rise once again, it will of course act as it does - to increase the size slightly.
I am NO talking about gyno growth of mammory gland tissue here.. i am talking about a mild but noticeable increase and decrease of volume.
(It should be made known that my gyno is not visible to others - only by touch and only on palpation).
So - yes Letro works to a degree - although only for small issues, and only temporarily. You do NOT need 2.5mg a day. you need a fraction of that to drop Estrogen to very low levels EVEN on cycle!
There is never a need to run 2.5mg - maybe unless you are using it for it's primary prescribed purpose.