It was a tough ride, she said, after being scouted at a Sevens tournament in Fiji and being asked to join the national squad, moving over to Fiji in December 2014.
Ms Coates' farmer father, Brett, is originally from Fiji, and his mum still lives there with other extended family.
"When I was given the opportunity to join the squad I just took it because it was an opportunity, and to represent Fiji really meant something to me and my family too," she said.
She was able to sit her university exams in Fiji, "which was just awesome", so she didn't have to choose between studies and training - which she describes as "probably the hardest thing I've ever done", especially in 30C heat.
Forcing herself to stay up and study after a full day of training "when your body just wants to rest" was difficult, she said.
On top of all that, she was also learning the language.
"It's been pretty crazy and now I'm just like, 'whoa I did it'."
She added: "It's been great, now I can speak Fijian with my grandmother, so it's been really special."
She credits her family with getting her through.
"They've been really supportive, especially at uni when there were times when I didn't know if I could actually do it."
She now hopes to combine her knowledge of Fiji, local culture and tradition, her love of sport and her nutrition qualifications to tackle Maori and Pacific rates of obesity and diabetes.
After the Olympics, of course: "I'm kind of just focusing on rugby at the moment."