The 'Leave' hitmaker - who is gearing up to put out her first album in 10 years, 'Mad Love' on October 14 - has opened up about feeling messed up "psychologically" after being pressured to shed the pounds she didn't need to lose.
In an interview with Popsugar, she revealed: "Here's something that I agreed to do that ended up messing with me psychologically. I was under a lot of pressure with a company I was at previously and they wanted me to lose weight fast.
"So they got me with a nutritionist and had me, like, on all these supplements, and I was injecting myself - this is a common thing 'the girls' do all the way - it makes your body only need certain calories, so I ate 500 calories a day. It was the most unhealthy thing I've ever done.
"I felt like, 'If I don't do this, my album won't come out.' Which it didn't! So it's not like it even worked!"
However, the 25-year-old pop beauty soon put the weight back on, but now she's happier within herself and has learnt not to follow other people's opinions.
She said: "I listen to other people's opinions. Listening and following are different things. I think listening and showing respect to people you respect . . . it works for me. What you think about yourself and the decisions you make is what's most important."
JoJo's new studio album 'Mad Love' will be released on Atlantic Records and is the follow-up to 2006's 'The High Road'.