CONOR McGREGOR gained two and a quarter STONE of muscle through a unique fitness and diet program.
After recovering from his horrific leg injury, the Irishman weighed in at 190lb or 13st 5lb.
This is almost two-and-a half stone more than Dustin Poirier's 11st 1lb that he weighed before he faced him at lightweight in July.
Spanish outlet AS interviewed Alejandro Celdran, a personal trainer, to discuss McGregor's methods.
Alejandro states that hypertrophy training, which increases muscle size, should be a priority.
He also advises that it is more important to do a minimum of four sessions per week for each muscle group.
It should range from six to fifteen repetitions, and 80 percent of the training should be dedicated to bilateral multi-joint exercise.
Alejandro claims McGregor may prioritise free weights over machines, also trying to do supersets, doing different exercises without rest between sets.
Free Bets: Get more than PS2,000 in NEW CUSTOMER DEALSMcGregor's diet consists of six meals per day. It includes foods such as chicken, fish and eggs.
For breakfast, you can choose cereals with eggs or sauteed vegetables. For a snack, you can choose fruit or a salad with honey for your morning snack.
McGregor will eat chicken breasts with rice and asparagus, and then he will have a vanilla shake with peanut Butter and walnuts for his snack.
McGregor's favorite Irish lamb stew with potatoes is another dinner, and McGregor finishes it off with a chocolate shake with organic coffee.
McGregor is just starting to hit the pads after his surgery. He's now focusing on strength.
He is so large that John Kavanagh, his head trainer, joked recently that he could fight at midweight. The pair will soon reunite.
McGregor, 33, was first back in January. He was defeated by Porier, 32.
He was then unable to finish round one of the trilogy bout, seven months later.
McGregor, who had a successful operation shortly afterward, is planning to return next year.
