Gabrielle Union is staying fit for her upcoming wedding, and she's doing it thanks to something she's dubbed "The Porn Diet."

It basically involves her following adult film stars around her local gym and doing whatever they do. Love it!

Also, it makes sense. Porn stars need to stay in shape to make a good living.

As Union revealed to host Conan O'Brien last night (Jan. 20), she'll make sure she exercises as much as them on the same machines (doesn't get off before them), and she also watches what they take in at the juice bar. Apparently, they seem to be mainly vegan.

So how does she recognize them? "I, you know, you see things," she joked, adding, "I recognize them ... 'I've seen your work, I love it. Let me get some tips. Not on that.'"

You can watch all of Union's tips for getting an amazing porn star quality butt in the clip above.