Phil Mickelson looked to switch up his routine after missing the cut in four of his last six events. He decided that it was his diet that needed to change a week before the Open Championship.

Mickelson, 49, finished in the top 20 at the Masters but failed to even reach the top 50 at the PGA Championship or the U.S. Open. He revealed Sunday that he made a drastic change to his diet, which included a six-day fast, that led to him losing 15 pounds.

MYSTERY, EXCITEMENT FOR BRITISH OPEN'S RETURN TO PORTRUSH

“Let’s get real for a few minutes,” he said in a video posted to his Twitter account. “I haven’t posted anything because I haven’t felt good about myself and the way I’ve been playing, so I haven’t done anything or wanted to be in public. The last 10 days I’ve done what I call a hard reset to change and try to make things better.

“I have lost 15 pounds. I’ve done a six-day fast with water and a special coffee blend for wellness that I’ve been working on with Dave Phillips, and went on a bit of a retreat. I’m here in Ireland now, a beautiful place, getting ready for the British Open. I don’t know if it’s gonna help me play better or not, but I’m willing to do whatever it takes to try to get my best back.”

The Open Championship, also known as the British Open, takes place at Royal Portrush in Northern Ireland and starts Thursday.

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Mickelson is coming off missing the cut at last week’s 3M Open and the Travelers Championship. Lefty last won a tournament in February – the AT&T Pebble Beach Pro-Am.