I'm about to begin HRT again, after about 5 years off of it, so perhaps I can have a bit of input. Personally, I wasn't very muscular to begin with either, and I still lost quite a bit of mass, but interestingly enough, not a lot of actual strength, I just got a lot slimmer. That has reversed itself quite a bit during my HRT hiatus, which hasn't been great for my dysphoria, but I did have a fair idea that it would happen. I'm just hoping I can lose enough again to visibly slim down again without losing a lot of strength. *crossing fingers*