After enjoying the Christmas break with family and friends, Parker joked that he now needed to drop some weight in preparation for a Fury showdown.
"I've put on a bit - I love those burgers and pies - but it's time to get back to work and focusing.
"I'm probably weighing 115-116kg, so would need to lose 5-6kg, but I haven't jumped on the scale yet. It may be more, who knows."
His return to training means he will be unable to attend two key events in his calendar - the Halberg Awards, where he is a finalist as Sportsman of the Year and Favourite Sporting Moment, and the NRL Auckland Nines, where he was due run water for the NZ Warriors.
"Sorry to the Warriors boys," said Parker. "I said I'd be there to support them and encourage them to pick up that trophy, but I'll watching from overseas."