He can already tick off Japan - he did that last year and it took him five months. He says he learned a lot from that trip, including not to carry a 25kg backpack the whole way.
"It was basically like a mobile home. My back was absolutely destroyed after that. Before I left I didn't realise what I was in for."
Mr Newburn's family had owned an Italian restaurant in Nebraska which contributed to him ballooning to 150kg by the time he was 17.
"I didn't have the best eating habits growing up ... and I got bullied like any overweight people would in school and I wasn't very motivated at all to do anything. My grades were kinda shit, I was sleeping in class a lot, I was just a lazy kid."
The only thing that kept him going was the Japanese card game Yu-Gi-Oh, which would prove to be the impetus for turning his life around. He was so devoted that after winning his local competition he went on to qualify for the World Championships in Tokyo in 2009 where he came 13th.
"It was then that I started having a different mentality on my life because I was able to achieve a dream since childhood ... If I can go to the world champs for this card game then I could lose this weight."
He got home and started running. Two years later he was clocking up 22km and went into the Navy. But during a social football game he broke his ankle, and complications brought his Navy days to a sudden halt.
Unsure what to do, a random phone call from a high school buddy planted the seed for him to head to Japan. Although his friend pulled out, he went anyway and decided to walk the country's length. While googling treks in Japan he found he could get a work visa in New Zealand, and discovered Te Araroa.
"I was like, this is a cross country trail from the very northern tip to the very southern tip, just like Japan. Then I think what's stopping me from continuing after Japan ... and then I just go crazy and think, why can't I just walk across the entire world?"
He chose to raise awareness and money for the aptly named Walk From Obesity, an organisation which motivates and hosts obese people on walks around the United States.
Mr Newburn has lived and trained in Queenstown for a year, saving $7500 while working at SkyCity casino. On holiday at home, he can't wait to get back to New Zealand to begin his trek on October 10.
"I'm a different person ... I want to continue travelling the world and meeting amazing people ... I'm ready to go."
• Follow Ryan Newburn's progress here
