NEW YORK — Not everyone was initially “All About That Bass.”

Meghan Trainor, the 20-year-old who is having a pop culture moment with the song about body acceptance, said she initially wrote the track and pitched it to other artists, but was turned away.

“Labels were like, ‘We love it, but you have to reproduce it. You got to get it more synth-y, pop-y,’ ” Trainor said.

Things changed when record executive L.A. Reid heard the doo-wop pop song and told Trainor she should be the voice behind it. He signed the budding songwriter to Epic Records after hearing her sing “Bass” while playing the ukulele.

This week, the song jumped 20 spots on the Billboard Hot 100 chart to No. 8. The single has sold 389,719 copies so far in five weeks, and the music video, which has 10 million views and climbing, has become a water cooler topic among young girls and parents.

“Bass” features standout lines like “it’s pretty clear, I ain’t no size two,” “I’m bringing booty back” and “yeah my momma, she told me don’t worry about your size.” Trainor said Grammy-nominated Kadish, who has worked with Jason Mraz, had the song title but didn’t know where to go from there.

“And I immediately thought, ‘Booty. Bass. Thickness,”‘ she said.

Trainor, who grew up in Nantucket, Massachusetts, moved to Nashville, Tennessee, where she wrote songs for Rascal Flatts and others.