It wasn't because he battled his own weight rumors (the National Enquirer claimed he weighed more than 200 pounds in 2008).
"Tony Romo is one of my favorite quarterbacks. I don't think he's my favorite but he's certainly one of my favorites. So I felt kinda conflicted doing the Jessica thing," he tells Detroit's Metro Times.
The rapper said he was originally going to have a skinny Jessica look-alike "come out and sing the chorus."
But then photos of a curvier Simpson surfaced, causing a change in plans.
"Jessica got fat," Eminem said. "I mean, not really fat, but she certainly got fat for ... well, Jessica Simpson got fat for Jessica Simpson! You know what I mean?"
To stay "within the current of what's going on right now in pop culture," he instead hired a voluptuous Simpson look-alike to strut around in Daisy Dukes and chow down a burger.
"I've always wanted people to be able to look back at each video and go, 'Oh, remember what was going on at that moment!'" Eminem said. "You know what I mean? 'Oh, that's when Jessica Simpson got fat.' 'Oh, OK!' And even if she gets thin again, that's fine. But for that moment in time, she was fat."
Still, he was nervous
Said the rapper, "I started thinking, like, 'Man!' I was telling [manager] Paul [Rosenberg] and everyone around me, 'Man, I don't wanna p--- Tony Romo off and he starts throwing games for the Cowboys!'"
More on Wonderwall:
More on Us Weekly:
- May. 03, 2016 Find out why Jay Z skipped the Met Gala, plus more news