Holm may not have made any defenses and lost her next three fights, but that pales in comparison to what former UFC heavyweight champion Barnett did.
After winning the belt from Randy Couture via second-round TKO at UFC 36, Barnett tested positive for anabolic steroid nandrolone even though he had been given a ‘warning’ (yes, that’s how drug testing in MMA went back then) when he also failed during his UFC 34 win over Bobby Hoffman. He had the belt stripped from him and went to fight in Japan for more than six years until he returned to compete for Affliction.
There, he was set to fight MMA legend Fedor Emelianenko but tested positive again, scrapping the bout and the promotion in the process. That wasn’t in the UFC, but Barnett eventually made his way back to the Octagon, where he won three out of five bouts from 2013-2016 before testing positive for an unprecedented fourth time in an out-of-competition test last December, making him the MMA fighter who has failed the most drug tests in history.