LOS ANGELES – It’s not exactly surprising to hear a fighter tell you how phenomenal he or she feels before a contest. Yet Quinton Jackson finds a way to make even that mundane proclamation unique.

“The No. 1 thing that I improved on is I cut out ketchup,” Jackson told reporters at today’s open workouts in Los Angeles. “You guys are laughing, but ketchup has probably been my worst enemy. I drown all my food in ketchup every meal I have, and I’ve finally cut it out.”

Jackson (37-12 MMA, 4-1 BMMA) faces fellow veteran Chael Sonnen (29-15-1 MMA, 1-1 BMMA) in the main event of Saturday’s Bellator 192 event at The Forum in Inglewood, Calif. The night’s main card airs on the newly rebranded Paramount, while prelims stream on MMAjunkie.

The matchup kicks off Bellator’s year-long heavyweight grand prix, which will crown the promotion’s next heavyweight champion.

Jackson has spent the vast majority of his career at light heavyweight, while Sonnen has largely competed as a middleweight, so the contest has a bit of an old-school, openweight feel. But even fighting up a division, Jackson insists diet has been at the center of his focus.

“Fighting at 205 pretty much my whole career, then not having to worry about weight, it’s a big stress relief,” Jackson said. “The whole weight thing has been my downfall for a long time. I didn’t know I had a thyroid problem.

“Even though I’m fighting at heavyweight, I still followed a strict diet. My coaches were like (expletive) about it.”

Jackson also competed at heavyweight this past March, tipping the scales at 253 pounds, though his frame didn’t exactly impress at the Bellator 175 contest. This time around, he appears to be in better physical condition, though he declined to reveal his exact weight.

“Me being a heavyweight, I know I’m under 265, so I haven’t weighed myself in a while,” he told MMAjunkie.

Since that last outing, Jackson has sought treatment for an under-active thyroid, a condition he said not only fatigued him but also made it nearly impossible to lose weight. Now, with medication, he says his body feels better than it has in years.

Oh, and the ketchup.

“I know I’m disciplined,” Jackson said. “I know I’m really motivated to win this tournament. I gave up ketchup, and that’s something that I’ve really loved since I was a kid.

“When I cut out the ketchup, that’s when (the weight) came off. As soon as I cut out the ketchup, you could see it in my face. It took like three or four days.”

Oddsmakers currently view Jackson as the favorite, though it will certainly come down to whether or not he can keep Sonnen’s wrestling attacks at bay. If successful, Jackson’s size and power advantages should see him through to a victory.

But Jackson believes with great sacrifices will come great reward, and potentially great violence, as well.

“Chael might decide, like, ‘Wow, what the hell am I doing in here?’” Jackson said. “You’ll see it. You guys can read his eyes.

“After the first minute or so, he’s going to be like, ‘Why did I step in this cage with ‘Rampage’?’ Because he won’t see Quinton. He’s going to see ‘Rampage.’”

To hear more from Jackson, check out the video above.

For more on Bellator 192, check out the MMA Rumors section of the site.