Phil Mickelson explains how he is addressing his recent poor play by fasting before The Open Championship. (0:46)

PORTRUSH, Northern Ireland -- Phil Mickelson decided to take drastic action in regard to his poor play of late by fasting for six days and losing 15 pounds.

The five-time major champion who won The Open at Muirfield in 2013, has been on a run of poor form since winning the AT&T Pebble Beach National Pro-Am this year, missing the cut in four of his past six starts.

"The last 10 days I've done what I call a hard reset to change and try and make things better,'' said Mickelson in a video he posted on Twitter.

Mickelson, 49, said he lost 15 pounds, in part by going on a six-day fast that included just water and a special coffee blend for wellness, as well as a brief retreat.

Since winning at Pebble Beach in February for his 44th PGA Tour title, Mickelson has posted just one top-20 finish, a tie for 18th at the Masters. He has finished outside of the top 30 on five other occasions.

"I don't know if it's going to help me play better or not,'' Mickelson said. "But I'm willing to do whatever it takes to try and get my best back.''