Story highlights Hospitalizations for children under 12 with eating disorders increase 112%

A psychologist sees third- and fourth-graders who are worried about being fat

Watch for a child who is cutting his or her portion sizes or avoiding fat calories

Swimming outdoors, playing with the family pet and enjoying an ice cream cone -- that is the summer life of a typical 9-year-old girl.

Not for Sarah Smith. As a child, Smith (whose name has been changed to protect her privacy) formed habits that would eventually lead her to develop both bulimia and anorexia nervosa, both of which she is still dealing with today.

Smith remembers her parents using food in a reward-punishment system. When she was good, she got treats; if she was bad, snacks were forbidden.

"I think there was a mixture of ... intentionally restricting my food and then going to try to find the food my parents were hiding," Smith said. "Even in childhood, it became sort of obsessive."

When Smith was born in 1989, child eating disorders were a rarity. Today, they are far more commonplace.

A study conducted by the Agency for Healthcare Research and Quality showed that hospitalizations for eating disorders in children under 12 increased by 119% between 1999 and 2006. More recent numbers are unavailable, but experts say the problem isn't getting any better.

Children will come in to her office already showing signs of malnutrition, dietician Page Love says. They often have low energy levels and low iron counts and are reporting hair loss because of their extreme weight loss.

Most, like Smith, do not recognize that their restrictive habits are actually an eating disorder that could ultimately be fatal.

Dina Zeckhausen is a psychologist and founder of the Eating Disorder Information Network . She sees kids in third and fourth grade who are already worried about being fat.

"There is so much emphasis on obesity," Zeckhausen said, "that there's a danger that we are going to produce a lot of anxieties in kids around weight."

Zeckhausen says that starting overweight kids on diets can trigger an obsession with food that could lead to an eating disorder. She recommends putting overweight children in a sport or becoming more active as a family and providing healthier food options.

Children at risk of an eating disorder share similar personality traits: high anxiety, perfectionism and obsessive-compulsive tendencies, according to Zeckhausen. They are also often subject to external pressures such as school bullying, abuse or a divorce. Restricting food intake is a way for a child to feel in control of their life.

"The eating disorder is the voice," said Love. "The eating disorder is a way to communicate (and say) 'I'm struggling. I'm hurt. I need help.' "

Smith's parents did not realize there was something going on until she was 13; her eating disorder was not professionally addressed until she was 17. As a result, Smith has been in and out of treatment facilities practically her whole life.

Experts say that getting help at a young age is the key to effective treatment.

"The longer an eating disorder goes on, the more potential physical and psychological damage can occur," Zeckhausen said. "It's particularly important to be in recovery before puberty begins so the child can accept and cope with the normal weight gain of puberty."

Love says that a lot of the time, she meets parents who say, "I didn't realize my child had lost this much weight until I saw them in a bathing suit."

"Unfortunately, some of these parents don't notice this weight loss until it's already significant," Love added.

A sudden change of portion size, cutting out foods the child enjoyed in the past, avoiding fat calories and sudden weight loss are all warning signs that a child is developing an eating disorder.

Smith said her family did not recognize her eating disorder as a problem. Now, a decade and a half later, she is still struggling.

"I think what I would tell them is to do their very best not to fool themselves," Smith said of her advice for children suffering with an eating disorder. "There are people out there, even if they aren't in their direct surroundings, who are filled with compassion and want to help."