"I like the idea of using the previous shots because there is no pressure to get in shape," she told the Herald. "And I won't need to spend two hours in the gym."
The model appeared naked in the September 2012 edition of the magazine and says she had to spend hours hitting the gym and avoiding sugary treats before the shoot.
"The shoot I did for Germany was just after January," she explained. "I had to have a super-healthy Christmas. I had to drink nothing but water – it was all very sad.
"And then we went to Mauritius with the family and they were all off drinking beer and eating this amazing food – I had to step away from the chocolate fountains and buffets."
The glamorous daughter of Chris de Burgh added: "I cut out alcohol for two and a half weeks before the shoot. Afterwards, I was just wolfing into everything and anything."
Rosanna has spoken about how liberating she found frolicking naked in the waves during the shoot.
"There is something very empowering about being on a secluded beach, naked in the warm air. It just felt very natural. I really enjoyed the experience," she said.
Rosanna has just finished her studies and is a fully-qualified nutritionist.
"The last six months have been hard," she said. "And it's nice to brush my hair and wear make-up again.
"I feel like all I've been doing is study. But I've started writing a health column for the BeautyLounge.ie – so it's nice to have landed my first proper job out of college."
Rosanna is currently in Berlin and is looking forward to relaxing and unwinding after hitting the books.
"I'm going to Marbella for a few days and will take some time off then," she said.