How does blocking estrogen help you build more muscle? What has estrogen got to do with testosterone production? There are two main hormones in men and women, testosterone and estrogen. Testosterone is dominant in men and estrogen is dominant in women. But interestingly, estrogen seems to be a signal to the pituitary gland in the brain. Based on estrogen levels, the pituitary turns on or off testosterone production. The higher the estrogen levels, the lower the amounts of testosterone will be produced. This is where anti-estrogen supplements come in!