Dear Mr. Colucci,
My humble suggestion is to create a transform challenge subsection.
Such subsection could be at any section you think could be appropriate. Something regarding body transformations.
The bro-user, like me, could annouce him/herself as a voluteer to establish some transformation as lowering bodyfat, increasing PRs, etc, etc. He/she could set a deadline to publish his/her transformation and, during the period, he/she could publish his/her partial achievements.
This kind of public commitment forces the bro-user to experience a real challenge.
It could be fun some kind of bell ringing event if the guy gives up, leaves the challenge, or does not achieve even x% of his/her goal.
Think about sir. The fun would be guaranteed.