That friend who never seems to eat around you may have a serious problem.

Five years ago, you would never have seen Leslie Lipton eating out. She was afraid to even open a menu.

"I assumed that everyone was watching everything that I put in my mouth and everything that I ordered. They must be making judgments about me …that I was too fat or lazy or a pig," Leslie explains.

The school cafeteria, dinner at her best friend's house, family get-togethers-- all caused anxiety attacks. Leslie was so self-conscious she stopped eating in public.

"For myself, I know that it was very much trying to control the way others would perceive me," Leslie says.

By 9th grade, Leslie was anorexic. Specialist Lynn Frefe says Leslie's shy eating behavior was an early clue. "Chances are if they're not eating in front of others, they're also not eating by themselves."

It usually starts in adolescence, and quickly spirals out of control. Mary Lipton is Leslie's mother, and says it was a hard time. "She wanted a hamburger but everyone else had just salad on their plate, so she couldn't have a hamburger. If you have two leaves of lettuce on your plate, I'm going to put one."

Not all shy eating is a symptom of an eating disorder. So how do you know it's serious? Dr. Bernardo Carducci works for the Shyness Research Institute at Indiana University Southeast.

"If you're going to go to a social function, who's going to be there, what are they going to be serving? You become preoccupied with that, so that you may think about not going," Carducci says.

Dr. Carducci recommends parents take action quickly. Mary agrees.

"Sit down with your child and say, 'look, is there anything wrong?' I'm getting concerned," Mary suggests.

Leslie is now recovered, and even wrote a book about her experience. The message?

"Recovery is definitely worth it. There's so many more important things that you can do with your life if you just, sort of, realize that food isn't the only thing," Leslie says.

Shy eating and other eating disorders don't just affect teens-- they can impact adults as well, especially in times of transition.