Victoria Justice has autoimmune disorder

Actress/singer Victoria Justice has been fighting a secret battle with Hashimoto's disease.

The former child star has opened up about her health struggles to Health magazine, revealing the side affects of the condition, in which the immune system attacks the thyroid, left her with acne and an ever-changing waistline.

"A few years ago, I was diagnosed with Hashimoto's, which is a thyroid autoimmune disorder," the Victorious star tells the publication. "All my life I've always had great skin, so it was really devastating.

"Also, at first, I was losing a lot of weight, then I went on tour and I started gaining weight, and it was the most I'd ever gained in my life. I was, like, 115 pounds. Then when I filmed a movie last summer, I actually went under 100 pounds."

Victoria admits her self-confidence took a knock as she dealt with the body issues in private, but she has since been able to bounce back with the help of her loved ones.

"(The bad skin) definitely did affect my confidence, and it made me a little bit more self-conscious," she reveals. "But at the end of the day, I had the support of my family and friends. I knew that the people around me had my back. Now I really empathize with people who have issues with their skin, because it can get you down."

The 22 year old is still fighting the disease, but she has since assured fans she is "back to normal".

She isn't the only celebrity to go public with her Hashimoto's diagnosis - Jane the Virgin star Gina Rodriguez was diagnosed with the condition last year (14).