The actress also revealed she no longer looks at herself in the mirror.
Jameela Jamil says her "loneliness" contributed to her eating disorder as a teen.
"The Good Place" star opened up to People about how her lack of friends when she was young made her disorder more severe. At age 14, Jamil developed anorexia and body dysmorphia after a class project required her to be weighed in front of the class.
"I was really unhappy," the actress recalled. "I think it contributed to my ability to have an eating disorder for so long, because there was no one kind of monitoring me and I had no one to turn to with my sadness and bad feelings, so I just had a really rough time as a teenager."
Because of the struggles she experienced as a teen, Jamil has teamed up with Bumble BFF, an app which encourages people to meet new friends.
"I've had lots of experiences with loneliness myself, and I wish that I had an app like this when I was a teenager, so that I could have met other people who were also looking for friendship and companionship," she said. "I'm socially awkward, and there was no set up to help socially awkward people admit they were socially awkward and that they needed a little bit of a boost to find friends."
She added, "I love the idea of de-stigmatizing the feeling of loneliness. Everyone gets lonely from time to time."
Jamil admitted that she eventually learned how to make friends, but it took some time. The native Brit added that her adult friendships have been "vital to her confidence" in Hollywood.
"I've learned how to suck it up and make an effort and put myself on the line and ask people out for coffee," she said. "I've even officially asked people to be friends, just to make sure that everyone's in agreement that there's some sort of friendship forming. I started doing more things that I love and meeting more people via that, and I've found more people who had the same interests."
"A friend is a witness to your life, which I think is something really beautiful and amazing and really shapes your bond with someone," she added. "We go through a lot as a woman or just generally as a human and having someone to share that with and having someone in your corner and tells you that you're wrong when you doubt yourself is so unbelievable. I don't think I would be the person that I am without my adult friendships and their love and support."
Jamil also spoke to the publication about the "radical inclusivity" platform she created called I Weigh, which has caught the eyes of many celebrities, including Sam Smith. Jamil said she uses some of the program's techniques for building confidence -- like making lists of her accomplishments and personality traits. She also doesn't look in the mirror.
"The only time I look in the mirror is when I put on my eyeliner in the morning and when I take it off at night," Jamil said. "I'm not interested in my appearance. I still suffer from body dysmorphia so it can be very distracting for me. Doing that has helped me concentrate on progressing and doing things that enrich my life, like watching my career grow and my relationships grow. That's what gives me a wonderful sense of self."