When American singer-songwriter Meghan Trainor dropped her single All About That Bass last year, it quickly became a chart-topping pop anthem around the world.

A doo-wop number with a catchy chorus, the Grammy-nominated song encouraged a positive body image, where "every inch of you is perfect, from the bottom to the top".

It did not just dominate the Billboard Hot 100 chart for weeks, it also managed to strike a personal chord with some of Trainor's fans, much to the surprise of the singer.

The 21-year-old breakout star, who was in town to perform at the Coliseum, Hard Rock Hotel on Thursday night, says at a press conference that her hit song made her realise "the power of a three-minute song".

"I wrote All About That Bass in 45 minutes. That's all it took, to apparently save lives and make people feel better."

Trainor adds that fans have come up to tell her that her song has helped them get through depression and even saved them from suicide.

"My goal was not to write really inspiring songs and inspire people, it just happened, and a lot of fans have expressed their stories and how they feel about my lyrics," she says.

Trainor was born and raised in Nantucket, Massachusetts, growing up in what she calls a "musical family", and crediting her dad, who was a musician himself, for supporting her pursuit of a career in music.

She started writing songs at age 13, and by the time she was 17, she had independently released three solo albums, two acoustic records and a pop record that mixed jazz and country influences.

She later began writing songs for other artists, including American country group Rascal Flatts and country singer Hunter Hayes. But she felt that was not enough.

"I knew when I got signed to be a songwriter, I knew there was something more, I just felt like I just can't be a songwriter in the background. Now, being an artist, I feel like 'A-ha! This is what I'm supposed to do'," she says.

That opportunity came with the release of All About That Bass, a song she co-wrote with songwriter and producer Kevin Kadish. She chose to record the song herself after it was reportedly turned down by other record labels and artists, including Beyonce and Adele.

She followed the success of All About That Bass with the next single Lips Are Moving, which peaked at no.4 on the US Billboard Hot 100 chart.

Her first major label album, Title, debuted at No. 1 on the music charts.

Riding on that high, Trainor is already working on material for her next album.

She hopes the new songs will inspire fans the same way All About The Bass did, hinting that one of the issues she could possibly highlight is online bullying, especially on social media platforms such as Twitter and Instagram.

"It's hurting a lot of people. It (social media) is very helpful for a pop star, but it hurts a lot of kids with all the comments and everything, and I think it almost makes them harsher, because they can think 'I'll never meet this person'."