Dr. Oz Issues Mark Wahlberg Push-Up Challenge Over Breakfast Battle

Dr. Oz is throwing down the gauntlet like we've never seen anyone do before -- daring to challenge shredded Mark Wahlberg to a physical fitness competition!!!

The so-called "BreakXit" controversy Dr. Oz started is NOT dying down ... and Monday in NYC he was prepared to go all-out to defend his belief it's time to cancel breakfast.

As you know, we got Mark out this weekend and he shot down the good Doc's theory. Turns out, Oz is taking that personally. He told us, he's reached out to Wahlberg for a sit down to come to some agreement about skipping breakfast.

And, get this ... he's also down for more than just talk the talk. Oz is challenging Wahlberg to a one-legged push-up contest -- and seems supremely confident he can beat the muscle-bound celeb without breakin' a sweat ... especially if Mark's got a bellyful o' breakfast.

Just in case he needs it, Oz is getting some backup from fitness guru Jillian Michaels. We don't know if she's down for the push-up competition, but she told us why Oz's breakfast theory is pretty on point.

Fresh off a wave of criticism following her comment about Lizzo's weight ... Jillian says science is never wrong!

Maybe, but we're not convinced science is enough for Oz to take down Wahlberg ... physically, at least.