The rotund Waratahs front row forward, who played in 24 successive Tests from the 2003 World Cup Final through to the 2005 year-end tour, said losing weight is what cost him his place in the Australian national side last year.
The 28-year-old Dunning, speaking to the media after his recall to the Wallaby side on Sunday, also missed a number of Super 14 games at the start of the just-completed Super 14 season through injury.
Dunning revealed that he had put on around eight kilos and was now up to around 121kg, which he regarded as his best playing weight.
“The last couple of years I’ve been looking more at keeping my weight down, so I went back to doing stuff I’m good at and working on my strengths, so I put a bit of weight on,” Dunning told the Australian Associated Press (AAP).
“That was aided by the injury I had earlier in the year, being in a knee brace for four or five weeks there’s not much else I can do.
“Mentally, I want to play and I enjoy coming to training and thinking about football, I probably wasn’t in that place in 2005 and 2006.
“Maybe keeping my weight down and not eating was making me irritable.”