Could insanity help grow muscle?

No.: Insanity does not contribute to muscle growth. A well design exercise regimen, proper diet and rest do.

I assume you: Are referring to the Beachbody workout system of "Insanity". If so, then yes. Realize that everyone's body may respond differently. If you are an experienced weight lifter/body builder you are more likely to "get lean" from a program such as this. Novice fitness people are likely to both lose weight but gain some muscle too