There are so many factors that can effect the sexual health of men and amongst them, there are two key factors that most commonly cause erectile dysfunction in aging men. And it is important to learn about these factors in order to understand whether the working process of this Krygen XL is legit or not. So according to this supplement, the first key reason men lose weight sexual performance over time is because of low testosterone levels. We are sure most of you are familiar with testosterone because it is the most important hormone that controls sex drive, libido and strength in men. So reduced levels of this hormone automatically effects sex drive of men along with muscle loss and poor energy levels. Second issue that this product claims to cover is poor blood supply to the penile muscles.