The high jumper made a splash last year when she took bronze at the European Indoor Championships in Apeldoorn, the Netherlands.
Nilsson's season continued in impressive style - but in February it came to a halt. She announced that her priorities going forward were her physical and mental health.
In the podcast Track and talk, Nilsson says that she suffered from an eating disorder.
"I suffered from some kind of eating disorder that caused me to lose twelve kilos, which is an extreme amount on a fairly slim body," she says, according to Expressen.
"I broke down my muscles. It became very mental, a lot of thoughts and my body couldn't handle it anymore."
The 20-year-old is back at a healthy weight, working out and aiming to compete outdoors.
