The typically harsh Simon Cowell called runner-up Katharine McPhee's voice "the best of the competition" on the most recent season of American Idol.

While it's no secret that legions of McPhans became captivated by McPhee's looks and talent on Idol, hardly anyone knew that she risked destroying it all during a five-year battle with bulimia. Self-induced vomiting put her ability to sing in serious jeopardy, not to mention the litany of health problems it exposed her to.

When McPhee hit bottom, she was throwing up as many as seven times a day.

"It's like putting a sledgehammer to your vocal cords," the 22-year old, native Californian tells People Magazine in its new issue.

After successfully auditioning for Idol last fall, McPhee finally decided to seek help.

"When I made it onto American Idol, I knew that food -- my eating disorder -- was the one thing really holding me back," Katharine said. "I was bingeing my whole life away for days at a time... So when I got on the show, I said, 'You know what? I can do well in this competition. Let me give myself a chance and just get ahold of this thing.'"

With the support of parents Peisha and Daniel, and her boyfriend, 41-year old actor Nick Cokas, McPhee enrolled at Los Angeles's Eating Disorder Center of California last October. She spent three months there in group and individual therapy sessions, six days a week.

"I knew I had put off going to a treatment center long enough. I'd been struggling with bulimia since I was 17," McPhee said. "Growing up in Los Angeles and spending all those years in dance class, I'd been conscious of body image at a young age, and I went through phases of exercising compulsively and starving myself. Food was my crutch; it was how I dealt with emotions and uncomfortable situations."

The Eating Disorder Center helped her gain control of her relationship with food, but it was far from easy.

"I really had to surrender and give up having a free life to do the program, because I'd be there from 9 in the morning until 7 at night... I remember that first night, my dad holding me, crying and saying, 'I don't know why you have to suffer through this, but it's going to be okay.'"

McPhee, who narrowly lost to Taylor Hicks on the show's finale, and whose first single will be released June 27, has dropped 30 pounds as a result of the "intuitive eating" approach she learned at the center.

"I learned that there's no such thing as a bad food. If you look at a doughnut, people think it's a fattening food... why? Because if you eat it you'll get fat? No, you'll get fat if you eat 10 doughnuts," she said.

While she has made great strides in conquering her eating fears, McPhee admits she's still coping with how to best handle stress.

"I still bite my nails," she said.

Matt Richenthal is the Editor in Chief of TV Fanatic. Follow him on Twitter and on Google+.