Georges St-Pierre is no longer the middleweight champion of the UFC.

A little more than a month after beating Michael Bisping to win the belt, St-Pierre has decided to vacate the title.

“My fight at UFC 217 was one of the greatest nights of my life but I now need to take some time to focus on my health,” St-Pierre said in a statement provided by the UFC. “Out of respect to the athletes and the sport, I don’t want to hold up the division. I will be giving up my belt and once I’m healthy I look forward to working with the UFC to determine what’s next in my career.”

Last week, St-Pierre was diagnosed with ulcerative colitis. That diagnosis led to his decision to vacate the title. He informed the UFC that he would be vacating the title earlier this week, sources said.

As a result, Robert Whittaker has been named the undisputed middleweight champion of the UFC. Whittaker won the interim title in July after beating Yoel Romero via unanimous decision.

Whittaker will now defend the title against former champion Luke Rockhold at UFC 221 on Feb. 10 in Perth, Western Australia. MMA Fighting first reported that fight on Thursday.

St-Pierre told TSN on Wednesday that he believes he got sick as a result of his move up to middleweight.

“After the fight, I thought first it was the stress that caused it and it would go away, but it did not go away,” St-Pierre said. “So what happened is even after the fight it persisted and I knew something was wrong so I let a few days pass by and after that I went to see a specialist. And I’ve been diagnosed with colitis, ulcer colitis, but now I have the medication and since I started medication it goes very well. So I’m almost 100-percent now.

“I feel much better now than before and also it’s a lot less blood so it’s good. It was a more scary and stressful situation for me than the actual reality. There’s different levels of colitis, I don’t think mine is very severe. Some people are stuck in a situation where it’s more severe and it can affect their well-being much more, but mine is not that bad.”

St-Pierre, 36, won the title against Bisping on Nov. 4 at Madison Square Garden after taking a four-year break from active competition. As a result, he became just the fourth fighter in UFC history to become champion in two different weight classes.

He also now becomes the first fighter to vacate a title in two different weight classes as he dropped the welterweight belt in 2013 prior to his hiatus.