Steven Taylor for iHeartRadio - iHeartRadio Music Festival 2017
Credit: Steven Taylor for iHeartRadio

Camila Mendes knows firsthand just how serious eating disorders are.

The Riverdale actress, 23, opened up about her struggles, and also those of her sister, on Instagram on Thursday.

Mendes talked about the serious health issue as she announced her involvement with Project HEAL – a nonprofit organization that helps people suffering with eating disorders pay for treatment.

“I can say from experience that eating disorders are serious mental illnesses,” she wrote on Instagram.

“Growing up, I watched my big sister suffer from one for many years, and I’ve experienced periods in my life when I’ve suffered symptoms as well,” she continued. “I’m joining Project HEAL to help break the stigma associated with eating disorders.”

Camila Mendes
Credit: CW

Mendes will be auctioning off a day on the set of Riverdale to raise money for the organization and encouraged her fans to look into the work the nonprofit was doing.

The star plays Veronica Lodge on CW’s breakout series, which is loosely based on the Archie comics.

Riverdale airs Wednesdays at 8 p.m. ET on The CW.