"I finally got in front of a mirror, without rationalising or camouflaging myself, and just thought, just do it," she said.
April hired a physical trainer and started a column for NZ Woman's Weekly about her mission, which also led to a Facebook page for women to share their own weight-loss stories, and eventually the book.
The eating and exercise plans were available online, and April said she wanted to ensure people who couldn't usually afford them were able to get on board.
"It's given me a different outlook because I've finally gotten to the end of a journey and been able to reflect back.
"All those simple keys people having been toting for years are true - just shut up and do it."
Though she is giving herself a holiday from the exercise regime during her two-week book tour, April has already set herself a new goal of running the New York marathon in November.
Masterton's Deb Morris bought April Loses It on the weekend and was already a third of the way through it.
Aiming to lose 30kg herself, she said it was easy to relate to April's story.
"It's what you're going through yourself, so it's real."
