By Edward Chaykovsky

According to Peter Fury, father and head trainer of undefeated heavyweight Hughie Fury, his son is packing on muscle for the upcoming world title fight with WBO champion Joseph Parker (22-0, 18 KOs), which is scheduled to take place on May 6.

Fury (20-0, 10 KOs) will travel to the champion's backyard of New Zealand for the mandatory challenge. The challenger has been out of the ring since last April, when he won a technical decision over veteran Fred Kassi.

Parker captured the word title last December, when he picked up the vacant belt with a very tough win over Andy Ruiz.

Peter Fury has a nutritionist working with his son, getting his body in top form and the fighter is adding on muscle on a weekly basis.

"Hughie is not ailing anymore. He's in very, very good condition. He's averaging a pound or two a week in added weight so he's going to come in his heaviest but also his leanest. He'll be in fine condition on fight night," Peter Fury told Isaac Robinson.

"Before, his insides were inflamed due to the spots breaking out on his body which caused open wounds and meant his immune system was fighting that. It was very difficult for him to put on muscle and any weight he did put on seemed to be fat. He was carrying a high percentage of body fat and it was a frustrating time. Now that's ended.

"He's taken on the nutrition now, is responding well to the training and is putting on lean muscle."

Peter says it is necessary to do everything possible in order to come to the champion's backyard to come back home with the title. The trainer expects a very hard fight and realizes the tough task at hand, to come to enemy territory to capture the title from a champion who is a superstar.

"When you're an away fighter, you've got it all to do and you've got to take it off the champion. You don't expect to get a fair, crystal clear decision -- you have to go and take it. This is the highlight of his career and it's a mountain to climb. Parker is a good fighter but Hughie is coming fully prepared to take those belts," Peter Fury said.