The biggest reason why beer is hard on your testosterone levels is because it is made from hops.
Hops are highly estrogenic, meaning that they actually contain estrogen, the hormone most tied to feminine behavior.
Hops contain so much estrogen, that women who pick them by hand must wear gloves in order to avoid side effects that impacted their menstrual cycles!
And the same hops used in your favorite beers are being studied to help with female hormone replacement therapy.