Lily Foster has been dancing since she was 3 years old, dabbling in tap, hip-hop and jazz and seriously studying ballet. She dreams of becoming a professional dancer.

"It’s my favorite thing to do," said the 16-year-old Honolulu girl.

But her dreams were threatened when at age 14 she was diagnosed with anorexia nervosa, a common eating disorder involving an intense fear of gaining weight. Sufferers severely limit their food intake and can become dangerously thin.

"I’m a perfectionist. … I went overboard with my perfectionism. I wanted to have the perfect body," she explained.

Foster attributes her rapid weight loss to the depression and isolation she felt after switching high schools. "I’d throw away my lunch, eat a tiny breakfast," she said. "I felt really depressed, sad and lonely. I had isolated myself. I was having trouble with friends."

Although she wasn’t eating, she was obsessed with food. "I’d watch the Food Network and view recipes online. I’d make stuff to feed someone else," she said.

After she dropped down to a mere 89 pounds on her then 5-foot-5-inch frame, her Hawaii State Ballet instructor John Landovsky went to her mother, Lori Foster, to voice his concerns and encourage her to seek professional help for her daughter.

"At first denial kicked in," Lori Foster said. "I had suspected that something was wrong, but you don’t want something to be wrong with your child. It’s difficult to think that they have a disorder. She was in puberty, and I wanted to believe that was the cause. Once I started reading about the symptoms and gaining knowledge, I set up an appointment with a nutritionist."

Lily continues to dance because it provides a positive force during her recovery, according to her mother.

"It was her passion. It was like dangling a carrot — she could continue to dance if her weight would go up," Lori Foster said.

She even performed as the Snow Queen and Sugar Plum Fairy in Hawaii State Ballet’s production of "The Nutcracker" last month.

"Family, school and the media can set the stage for an eating disorder. It’s an attempt to cope with emotional stressors," said Anita Johnston, clinical director of the ‘Ai Pono Intensive Eating Disorders Programs.

"Anorexia and exercise addiction with the goal of weight loss are extremely harmful. It can start as early as age 9."

Johnston holds a doctorate in psychology and has been working with eating disorders since 1982. She said complete recovery comes when the underlying issues, such as those mentioned by Lily Foster, are addressed.

Some signs to look for include hiding under layers of clothing, mood swings, restricting food consumption or narrowing food choices, such as adopting a vegetarian diet or eating in private.

Reasons some individuals are susceptible to eating disorders vary, she said.

"It’s like a soup that includes a lot of ingredients; personality type, trauma, dysfunctional family issues can be factors. These issues load the gun, and a diet is what pulls the trigger. Diets are so dangerous and we are a diet-oriented culture," she explained.

Dancers, gymnasts, ice skaters and models are particularly vulnerable, Johnston said. Boys also can suffer from eating disorders, especially wrestlers and other athletes who face pressure to "make weight."

In many cases both a dietitian and a therapist are needed to help during the recovery process.

Registered dietitian Kristen Lindsey-Dudley of Nutrition Therapy Consultants says parents should be concerned whenever their children start dieting or become too focused on food.

"No kid should be dieting. They shouldn’t be looking up calories and fat content of foods on the Internet," she said.

It’s best to get help before the situation progresses to an eating disorder, Lindsey-Dudley added.

However, doctors might dismiss the problem because the child’s weight may still be in a normal range. "Pediatricians see so much obesity, they aren’t necessarily considering eating disorders. We’re trying to get parents to see the early signs of an eating disorder," she said.

Lindsey-Dudley has been working with Foster and acknowledges her progress. The teen is in a challenging situation because she continues to pursue ballet. "We still need to keep a close eye on her," she said.

Foster explained that "it’s hard having mirrors all around" at the dance studio. "I have to force myself not to look at other girls and make comparisons. I have lots of support but ultimately it’s up to me. I have to love myself."

Foster’s treatment was twofold, including nutritional coaching to get her weight back up and therapy with a psychiatrist to deal with control issues.

"It’s all about control," the teen said. "I felt a lack of control and needed a grasp on life. I needed to be in control of one thing."

She is thankful her family and dance instructor led her to help. "Eating disorders are hidden under the rug. People may not understand that it’s a fatal disorder," she said.

Foster said the media project images that make women hate themselves and their bodies. "I’d obsessively look up the height and weight of celebrities. I was always comparing myself with others. My eating disorder was the only thing I trusted," she said. "I don’t know my current weight. I’d get hooked on the number."

Foster realizes her recovery might take some time and that feelings of stress, tiredness, anger or sadness could trigger a relapse. But she remains positive and has stopped reading certain magazines and diet websites. She also deleted her Facebook account to avoid the weight-related photos and comments often exchanged via social media.

She says being open with her feelings is critical to her recovery. "Being able to confront people and get things off my chest has really helped," Foster said.

One of her main goals is to maintain a healthy balance between ballet, which she practices six times a week, and her social life.

And she continues to dream about becoming a principal dancer in the Royal Ballet in London.