From 170kg bouncer to All Blacks prop - the rise of Karl Tu'inukuafe

Freshly minted All Black prop Karl Tu'inukuafe says rugby was 'just a way to lose weight and stay in shape' ahead of his Test debut against France.

Tu'inukuafe's meteoric rise from out of shape bouncer to an All Blacks prop saw him lose 40kg of bodyweight, which he was told he had to do if he wanted to avoid a heart attack in his early twenties.

Now slimmed down to 135kg, the Chiefs prop is set to become the second heaviest All Black of all time, behind 136kg Nemia Tialata.

"It's a huge privilege and honour and I would like to do that for what they did for my family," he told AllBlacks.com.

All Blacks headcoach Steve Hansen admits luck has played a hand in his selection.

"He's had a few marbles roll his way. I mean, the Chiefs looseheads [props] have been dropping like flies all year and he's stepped up and really done the job," he said.

"I'd never heard of him before he got to the Chiefs, and I don't think the Chiefs had either until they had to go and find him," he said. "He just slotted in. That Chiefs scrum is very strong and he's a big part of that."

According to allblacks.com the 25-year-old loosehead first came to prominence back in 2010 as part of the massive First XV front row at Auckland's Wesley College, where he propped alongside fellow Chief and All Black Nepo Laulala.

Tu'inukuafe made Counties Manukau age-grade teams and then took a couple of seasons off before kick starting his career with North Harbour in 2015.

He spent a season in French club rugby before returning home and was called into the Gallagher Chiefs squad late last year by Coach Colin Cooper, initially in a development capacity. But injuries have seen him make the matchday squad regularly since round five and he has impressed so far in his debut Investec Super Rugby season.