(CNN) -- Playing Meadow Soprano on HBO's pilot of "The Sopranos" was the role of a lifetime for then-16-year-old Jamie-Lynn Sigler, an unknown actress from Long Island, New York.But little did anyone know that when the show debuted in 1999, Sigler was on the verge of taking her life due to her struggle with an eating disorder."I seriously contemplated suicide," said the actress, who now goes by her married name -- Jamie-Lynn DiScala in an interview with CNN's Paula Zahn. "I felt that no one in this world would ever understand the constant battle I had in my head every day."Exercise bulimia 'interrupts your life'DiScala was suffering from exercise bulimia. Exercise bulimics work out to "purge" what they have eaten in much the same way bulimics vomit after eating. Chronic, obsessive exercise is accompanied by a vigilant, nearly compulsive focus on calories.Doctors are still learning about this form of bulimia and there are no strict guidelines for diagnosing this disorder."The difference between a lot of exercise and exercise bulimia is when an individual is willing to cancel their whole life to fit in exercise," said psychologist Douglas Bunnell, past president of the National Association of Eating Disorders and clinical director of the Renfrew Center of Connecticut. "Whether it's missing work or a meeting to fit in that long workout, exercise bulimia functionally impairs and interrupts your life."DiScala said her battle with the disorder began when her high school boyfriend broke up with her. Devastated and depressed, she started to question her looks and her body. She became concerned about every calorie that went into her mouth and obsessed with burning every last one through exercise."I started maybe just doing like 20 minutes on the treadmill before school and then deciding on I wasn't gonna have any dessert anymore," she recalled.DiScala was encouraged by the resulting weight loss."When I saw the scales start to go down, well, then, I thought, 'Well, what happens now if maybe I exercise an hour before school and don't eat bread?' "Her idea turned into waking up at 3 a.m. to exercise for four hours before school and eating next to nothing.She then tried to find new ways to burn more calories apart from exercise such as frequently asking to go to the bathroom so she could walk to and from class and fidgeting. She saw her breakfast routine as an opportunity to burn calories as well."I would set things so far apart on the counter where I would have to walk up and down the kitchen counter to make it just so I can constantly be burning calories," she said.'It was awful'Within four months, DiScala weighed a mere 80 pounds."I was wearing basically children's clothes. It was hard to find clothes that would fit," she said."Every week I would see my reflection of my back and see more bones coming out, more ribs and more hip bones. It was awful."DiScala said exercise, calories and the scale ruled her life even though she longed to do the things that any teenager wanted to do like sleep in and hang out with her friends."I really wanted to just be comfortable and be happy, but I didn't think it was possible ever again. And I just didn't know how to get past it." Further, DiScala says admitting she had an eating disorder meant failure to her.During this low point in her life came what should have been a high point in her career when in November 1997, DiScala learned that HBO would be picking up the series. But she was under the spell of her eating disorder and nothing else mattered. "It was like in one ear and out the other because I was too concerned about what I was going to be having for lunch that day. And I truly lost a will to live."Her rock-bottom moment came on a drive with her parents into New York City to go rollerblading. After leaving their house more than 45 minutes late, DiScala's strict exercise and eating schedule was completely disrupted -- a disaster for an exercise bulimic."I was shaking and crying in the back of the car and my parents were crying because they didn't know what to do," she said.DiScala admitted then to her parents that she had an eating disorder and wanted help. The next day she saw a therapist and a nutritionist and was put on Prozac.Road to recovery and advocacyDiScala began to eat and modify her exercise and started gaining weight. But when she returned to "The Sopranos" set to shoot the first season in the summer of 1998, she was still 35 pounds thinner than when she shot the pilot. Worried that she'd be too weak to do her job and that she didn't look the part of a Mafia daughter, whose family sustained themselves on platefuls of pasta, show producers began auditioning other actresses for the role. But DiScala vowed to hold on to the part she had dreamed of and within a year, she gained back all the weight.Now, DiScala serves as the spokeswoman for the National Eating Disorders Association. She's also shared her own personal story in her autobiography "Wise Girl."And while she's let go of her eating disorder, she still holds on to one reminder in her wallet: a picture of herself at her lowest weight."I thought that that was my life. I was set. This was the way I was going to have to live my life," she said. "And knowing that I was able to overcome it and be healthy and happy again is amazing."CNN's Paula Zahn contributed to this report.